CBSE Solutions for Class 10 English

જવાબ : ohm-metre (Ω m)

જવાબ : length, area of cross-section, material

જવાબ : Ohm’s, current, temperature

જવાબ : ampere

જવાબ : Nitrogen

જવાબ : Electric power

જવાબ : Low

જવાબ : Electric Current

જવાબ : Voltmeter

જવાબ : Positive, Negative

જવાબ :  

જવાબ : Voltmeter.

જવાબ : Work done per unit charge in moving a unit positive charge from one point to another point in an electric field is called potential difference between two points.

જવાબ : Electric potential is a scalar physical quantity.

જવાબ : Electric potential is said to be 1 volt if 1 Joule of work is done in moving 1 coulomb charge from infinity to a point in the electric field.

જવાબ : volt.

જવાબ : V = W/q.

જવાબ : Electric potential at a point in an electric field is defined as the work done in moving a unit positive charge from infinity to that point in the electric field.

જવાબ : doubled

જવાબ : Potential difference across the ends of the conductor.

જવાબ : Electric current is defined as the amount of electric charge flowing through any cross-section of a conductor per unit time.

જવાબ :

જવાબ : Electric current through a conductor is said to be 1 ampere if 1 coulomb electric charge flows through a cross-section of a conductor in 1 second.

જવાબ : ampere (A)

જવાબ : I = ne/t.

જવાબ : Ohm’s law states that the electric current flowing through a conductor is directly proportional to the potential difference across the ends of the conductor, provided the temperature and . other physical conditions of the conductor remain the same.

જવાબ : Voltmeter is connected in parallel across a conductor or resistor in the electric circuit.

જવાબ : Ammeter is connected in series in an electric circuit.

જવાબ : Ammeter.

જવાબ : The direction of electric current in a wire is just opposite to the direction of flow of electrons in the wire.

જવાબ : The potential difference (V) is directly proportional to the current (I).

જવાબ :

જવાબ : V ∝ I or V = IR or I = V/R .

જવાબ : It is the property of a conductor to oppose the flow of electric charge through it.
Resistance of a conductor, R = V/I , where V is the potential difference across the conductor and I is the current flowing through the conductor.

જવાબ : ohm (Ω).

જવાબ : Therefore, slope of V-I graph represents reciprocal of the resistance of a conductor resistance of a conductor.

જવાબ : y = R. Therefore, physical quantity is resistance of a conductor.

જવાબ : A straight line passing through the origin and has constant slope.

જવાબ : The resistance of a conductor is said to be 1Ω if a potential difference of IV across the ends of the conductor makes a current of 1A to flow through it.

જવાબ : Slope of I-V graph = resistance of metallic conductor.
Since, slope of I-V graph at temperature T₂ is greater than the slope of I-V graph at temperature T₁, therefore, resistance at T₂ is greater than resistance at T₁ . Since, resistance of a metallic conductor increases with increase in temperature, therefore, T₂ > T₁.

જવાબ : Resistance of a conductor increases with the increase in temperature.

જવાબ :
where R is the resistance, A is the area of cross-section and l is the length of the substance.

જવાબ : Resistance of a wire is inversely proportional to its cross-sectional area. More is cross-sectional area of a conductor, less is the resistance of the conductor.

જવાબ : R_eff = R₁ + R₂ + R₃ + … upto n = nR

જવાબ : Resistivity of metal < resistivity of alloy < resistivity of insulator.

જવાબ : New resistivity will also be ‘ρ’ because resistivity of a wire does not depend on its length.

જવાબ : ohm-metre (Ω-m).

જવાબ : Electrical resistivity of a material is defined as the resistance of an object (made of the material) of unit length and unit area of cross-section.

જવાબ :

જવાબ :

જવાબ : (a)(i) Ammeter reading in the second case is half of the ammeter reading
in first case. This is because
=> i.e. when length is doubled, the resistance is doubled, this means the current is halved.
(ii) On doubling the area of cross-section without changing the length of the conductor, twice of the previous reading is observed in the ammeter. This is because
So, when A is double, resistance becomes half, current will be doubled. (b) “Potential difference between points A and B in an electric field is 1 V”. It means 1 J work is done in moving 1 C of charge from point B to point A in an electric field.

જવાબ : (a) Electric line wires offer extremely low resistance to the flow of current, so
they do not glow because negligible heat is produced in it.
The filament of bulb glows because it becomes red hot due to large amount of
heat produced, as it offers high resistance to the flow of current through it.
(b) The filament of bulb when it glows at 2700°C does not get burnt because the tungsten metal of filament has
(i) a very high melting point (of 3380°C) and
(ii) a high resistivity.

(c) Given: I = 0.25 A, t = 4 h = 4 x 60 x 60 sec.
So, amount of charge flowing the filament of electric lamp
So, the capacity of the fuse that should be used for the electric iron is of the order of 10 A.

જવાબ : The resistivity of nichrome is more than that of copper so its resistance is also high. Therefore, large amount of heat is produced in the nichrome wire for the same current as compared to that of copper wire. Accordingly, more change in temperature is observed in the nichrome wire. This is explained by Joule’s law of heating.

જવાબ :

જવાબ : (i) Bulbs in parallel provide more illumination. This is because
(a) each bulb gets same voltage and is equal to the applied voltage.
(b) each bulb draws required current from the mains. Hence, they work properly.
(ii)When one bulb in each circuit get fused,
In series: Rest of the bulbs will not glow. This is because in series arrangement, there is only a single path for the flow of current.
In parallel: Rest of the bulbs will continue to glow as in parallel connection,
(a) individual branch in the circuit completes its own circuit, or
(b) different paths are available for the flow of current.
(iii) Circuit diagram

જવાબ : Power of the bulb,

જવાબ : (a) Electric power: It is the rate of doing work by an energy source or the rate at which the electrical energy is dissipated or consumed per unit time in the electric circuit is called electric power.

 

જવાબ :

જવાબ :
Aim: Same current flows through every part of the above circuit.
Procedure:

1. Connect ammeters, ‘A’₁ between B and C, and ‘A₂’ between D and E.
2.  Adjust the sliding contact of the rheostat initially for a small current.
3. Note all the ammeter readings. These reading give us current flowing through the resistors R₁, R₂ and R₃
4. The current in the circuit is now increased by changing the position of sliding contact J’ of the rheostat.
5. Note all the ammeter readings each time.

1. All the connection should be tight and properly connected as per circuit diagram.
2. The positive terminal of the ammeter and voltmeter must be connected to the positive terminal of the battery or battery eliminator.

જવાબ : Greater than slope of V-I graph, greater will be the resistance of given metallic wire. In the given graph, wire A has greater slope then B. Hence, wire A has greater resistance.
For the wires of same length and same thickness, resistance depends on the nature of material of the wire, i.e.

જવાબ : Ohm’s law : When the physical conditions such as temperature etc. remain same, the current flowing through the conductor is directly proportional to the potential difference applied across the ends of the conductor, i.e.,

Necessary condition for validity of Ohm’s law is that physical condition such as
temperature of the conductor remains same.
Procedure:
(i) Complete the circuit by connecting one cell in the gap XY. Plug the key.

(ii) Note the reading in the ammeter for the current I and in the voltmeter for the potential difference, (V) across the nichrome wire.

(v) Find the ratio of F to / for each observation.
(vi) Plot a graph between V (y-axis) and I (x-axis).
Observation :

1. Voltmeter and ammeter reading increases as the number > of cells increase in series.
2. Same value of V/I is obtained in each case.
3.  V-I graph is a straight line passing through the origin of the graph as shown.
   

જવાબ : Mathematically, resistivity of the conducting material is given by
p = R x A/J
If l = 1 m, A = 1 m², then p = R
Hence, the resistivity of the material is defined as the resistance offered by a metallic wire having a unit length and a unit area of cross-section. Since unit length and unit area of cross-section forms a cube, the specific resistance or resistivity can also be defined as the resistance offered by a cube of a material of side 1 m when current flows perpendicularly through the opposite faces. In SI system, its units is

Experiment:
Aim : To study the factors on which resistance of conducting wires depends. Apparatus Required : A cell, an ammeter, nichrome wires of different length but same area of cross-section (thickness), nichrome wires of same length but different thickness, copper and iron wire of the same length and same thickness as that of any nichrome wire.
Procedure :

1. Connect the cell, an ammeter and plug key in series with nichrome wire of length T (marked 1) in the gap XY as shown.
   
2. Close the key and note the reading of ammeter. It measures the current ‘I’₁ through the nichrome wire (marked ‘1’).
3. Replace the marked 1 wire with another nichrome wire having same area of cross-section (thickness) but of double length’2l’ (marked 2).
4. Note the ammeter reading (I₂) again after closing the key.
5. Again replace the marked 2 wire with marked 3 wire which has the same length but is thicker than marked 1 and 2 nichrome wires. Again note down the current (I₃) through this wire.
6. Unplug the key. Remove marked 3 nichrome wire from the gap XY. Connect the copper wire marked 4 having same length and same area of cross-section as that of nichrome wire marked 1. .
7. Plug the key again and note the ammeter reading. It measures the current (I₄) through copper wire.
8. Repeat the experiment with iron wire and measure the current (I₅).

1. Current ‘ I’ is half ofI₁ i.e., I₂ =1/2 I₁
2. Current I₃ increases when thicker wire of same length and of same material
   i. e., nichrome is used.
3. Current I₄ and I₅ is different for copper and iron wire.

1. Different wires drew different amount of current from the same cell.
2. First observation indicates that the resistance of the conductor increases with increase in length. So, resistance is directly proportional to length.
3. Second observation shows that thicker wires have lesser resistance. So, resistance is inversely proportional to area of cross section of the wire.
4. Third observation shows that resistance of the conductor depends on the nature of its material.

જવાબ :

• Electric Current: The amount of charge ‘Q’ flowing through a particular area of cross section in unit time ‘t’ is called electric current, i.e.
• Electric current, I = Q/t
•  SI unit of electric current is ampere.
•  One ampere of current is that current which flow when one coulomb of electric charge flowing through a particular area of cross-section of the conductor in one second, i.e. 1A = 1 Cs^-1.

જવાબ :

જવાબ :

જવાબ :

જવાબ : For Ohm’s law: Ohm’s law states that the electric current flowing through a conductor is directly proportional to the potential difference across the ends of the conductor, provided the temperature and . other physical conditions of the conductor remain the same.
For experimental verification: Verify Ohm’s law
Apparatus : A conductor of resistance R, an ammeter, a voltmeter, a battery, a variable resistance (or rheostat used to change the current in the circuit), connecting wires, a key and sand paper.
Procedure:

1. 1. Connect the various components as shown in figure 12.
      
   2. Close the key, so that current begins to flow in the circuit.
   3. Note down the potential difference (V) across the conductor PQ of resistance R shown by the voltmeter and the corresponding current (I) shown by the ammeter.
   4. Now move the knob of rheostat so that the current in the circuit increases.
   5. Again note down the potential difference (V) across the conductor PQ of resistance R in the voltmeter and current in the circuit shown by ammeter.
   6. Repeat the experiment at least five times by increasing the current in the circuit by moving the knob of the rheostat in steps.

જવાબ : Electric power is defined as the amount of electric work or electric energy per unit time.
If W be the amount of electric energy consumed in a circuit in t seconds, then the electric power is given by

જવાબ : Heat produced in a heater, when connected to main supply,

When identical heaters (i.e. having same resistance) are connected in parallel, their net resistance decreases as compared to when connected in series. Therefore, heaters connected in parallel would heat the water faster as the heat produced in parallel combination is more than the heat produced in series combination, on electric energy and electric power

જવાબ : It should be made of nichrome wire because

1. resistivity of nichrome is greater than that of iron and silver,so more heat is produced in the nichrome wire due to the flow of current.
2. melting point of nichrome wire is greater than that of iron and silver and hence it does not melt easily on heating.
3. nichrome wire does not oxidise (or burn) easily even at higher temperature.

જવાબ :

Salient features of series combination :

1. The net resistance of the combination is equal to the sum of the resistances of the individual resistor.
2. The current flowing through each resistor is the same.
3. The voltage applied across the series combination of resistors is equal to the sum of potential differences across the individual resistors.

1. The reciprocal of the net resistance of the combination is equal to the sum of the reciprocal of the resistances of the individual resistors.
2. Different amount of current flows through each resistor.
3. The potential difference across each resistor is equal to the voltage applied across the combination.

જવાબ : The given circuit is incorrect because in a circuit, ammeter is always connected in series and voltmeter is connected parallel to the resistor R₁. The correct circuit is shown in figure.
 

જવાબ :

1. Resistance of a conductor depends on the length and area of cross-section of the conductor. On the other hand, resistivity of a conductor is independent of length and area of cross-section of the conductor.

જવાબ : Resistance of a conductor = slope of I-V graph. It means, resistance is high if slope of I-V graph for it is steeper. Since R₁ > R₂, therefore, slope of I-V graph for R₁ must be steeper than the slope of I-V graph for R₂ Thus, diagram I represents the situation correctly.

જવાબ : The current in the circuit is high if the resistance of the circuit is low. Since wire A is longer than B, so the resistance of wire B is less than the resistance of wire A. Hence, current flowing through wire B is greater than the current flowing through wire A. Therefore, ammeter A₂ will indicate higher reading of current.

જવાબ : Answer:
 
p and l for both wires A and B are same but area of cross-section (A) of wire A is- more than the wire B. Therefore, resistance of wire A is less than the resistance of the wire B. Hence, ammeter A connected in series with the wire A will indicate higher reading for current.

જવાબ : (i) It represents a closed plug key. It is used to make the closed electric circuit.
(ii) It represents a variable resistance. It is used to increase or decrease the electric current in the circuit.
(iii) It represents a voltmeter. It is used to measure the potential difference across a resistor in the circuit.
(iv) It represents a galvanometer. It is used to detect the presence of small current in the circuit.
(v) It represents wire crossing (not connected with each other). The wires are used to connect various components in the circuit.

જવાબ : electric circuit:
An electric circuit is a closed conducting path containing a source of electric energy (i.e., a cell or a battery) and a device or element or load (say, an electric bulb) utilizing the electric energy.
The direction of electric current is opposite to the direction of the flow of electrons in the conductor.
Open electric circuit : An electric circuit through which no electric current flows is known as open electric circuit.
The electric circuit shown in figure 10 (A) will be open circuit if the plug of the key is taken out or if the connecting wire breaks from any point.

Closed circuit : An electric circuit through which electric current flows continuously is known as closed circuit (Figure 10 (B)).

જવાબ :

જવાબ : Electric current is defined as the amount of charge flowing through a cross-section of a conductor in unit time.
 
SI unit of electric current is ampere (A).
Electric current through a conductor is said to be 1 ampere if one coulomb charge flows through a cross-section of the conductor in one second.

જવાબ :

જવાબ :

a. Bulb is usually filled with (nitrogen)
b. SI unit of current (ampere)
c. Flow of current in a wire is due to (potential difference)

જવાબ :

a. The device which measures current (ammeter)
b. The device which measures potential difference (voltmeter)
c. The device which protect electric appliances from high current (fuse)
d. SI unit of voltage (volt)
e. Combination used for household use (parallel)
f. Commercial unit of energy (kilowatt hour)