Class 10 Science NCERT Electricity

Q 11 :
The proper representation of series combination of cells for obtaining maximum potential is:

1

2

3

4

(1)

The maximum potential is obtained when cells are connected in series such that the negative terminal of the first cell is connected to the positive terminal of the second cell and so on.

Q 12 :
The equivalent resistance of a series combination of two resistances is X ohm. If the resistances are of $10 Ω a n d 40 Ω$ respectively, the value of X will be:

$10 Ω$
$20 Ω$
$50 Ω$
$40 Ω$

1

2

3

4

(3)

$R = R_{1} + R_{2} R = 10 + 40 = 50 Ω$

Hence, the value of X is $50 Ω .$

Q 13 :
A cylindrical conductor of length l and uniform area of cross-section A has resistance R. The area of cross-section of another conductor of same material and same resistance but of length 2l is:

0.5 A
1.5 A
2 A
3 A

1

2

3

4

(3)

For a conductor, $R = ρ \frac{l}{A}$

$\frac{R_{1}}{R_{2}} = (\frac{L_{1}}{L_{2}}) \times (\frac{A_{2}}{A_{1}}) A_{2} = (\frac{R_{1}}{R_{2}}) \times (\frac{L_{2}}{L_{1}}) A_{1} A_{2} = (\frac{R}{R}) \times (\frac{2 l}{l}) A A_{2} = 2 A$

Q 14 :
The maximum resistance which can be made using four resistors each of resistance $\frac{1}{2} Ω$ is

$2 Ω$
$1 Ω$
$2.5 Ω$
$8 Ω$

1

2

3

4

(1)

The maximum resistance which can be made using four resistors each of resistance $\frac{1}{2} Ω i s 2 Ω$ . This can be explained as: In series combination, the current in each resistor remains constant and the voltage gets added up. As a result, the individual resistances also get added up.

So, Equivalent Resistance $= R_{1} + R_{2} + R_{3} + R_{4}$

$= \frac{1}{2} + \frac{1}{2} + \frac{1}{2} + \frac{1}{2} = \frac{4}{2} = 2 Ω$

Q 15 :
A piece of wire of resistance R is cut into five equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is R' then the ratio $\frac{R}{R'}$ is

1/25
1/5
5
25

1

2

3

4

(4)

Given, a piece of wire with resistance R is cut into 5 equal parts

$\frac{1}{R^{'}} = \frac{5}{R} + \frac{5}{R} + \frac{5}{R} + \frac{5}{R} + \frac{5}{R} \frac{1}{R^{'}} = \frac{25}{R}$

now, these pieces of wire are connected in parallel then the resistance is (R')

$\frac{1}{R'} = \frac{5}{R} + \frac{5}{R} + \frac{5}{R} + \frac{5}{R} + \frac{5}{R} S o, \frac{1}{R^{'}} = \frac{25 R}{R} R^{'} = \frac{R}{25} N o w, \frac{R}{R'} = \frac{\frac{R}{R}}{25} \frac{R}{R'} = \frac{25}{R} \frac{R}{R'} = 25$

Q 16 :
On which of the given factors, resistance does not depend:

length of conductor
area of cross-section
temperature
density

1

2

3

4

(4)

The resistance of a wire can be expressed as:

$R = ρ \frac{L}{A}$

Where,
A = Area of cross-section of the conductor
L = Length of the conductor
$ρ$ = Resistivity

From the above relation, we can see that resistance of a wire is directly proportional to its length and inversely proportional to the area of cross-section. Hence, resistance does not depend on the density.

Q 17 :
Which of the following obeys Ohm’s law?

Filament of a bulb
LED
Nichrome
Transistor

1

2

3

4

(3)

In conductors, resistance remains constant when the current passing through them is increased; they are known as Ohmic conductors. Nichrome, which is an alloy, is made in such a way that its resistance remains constant for a wide range of temperatures. Hence, nichrome obeys Ohm’s Law. Whereas, transistor, LED, bulb filament do not obey Ohm’s law because with the varied change in temperature, their resistance changes.

Q 18 :
Electrical resistivity of an alloy of copper and nickel is _______ when compared with the electrical resistivity of an alloy of copper, manganese and nickel.

same
double
more
less

1

2

3

4

(3)

Electrical resistivity of an alloy of copper and nickel is more when compared with the electrical resistivity of an alloy of copper, manganese, and nickel. The electrical resistivity of Cu-Ni alloys with increasing temperature rises steeply. At 200°C, the electrical resistivity of Cu-Ni alloy is $49 \times 10^{- 8} Ω . m$ whereas that of copper, manganese, and nickel is $49 \times 10^{- 8} Ω . m$

Q 19 :
There is a dual of 8 ohm resistance on the aerial. Determine the aerial’s new resistance.

$2 Ω$
$4 Ω$
$7 Ω$
$10 Ω$

1

2

3

4

(1)

Let ( l ) be the length and ( A ) be the area of cross-section.

$R = ρ \frac{l}{A} = 8 Ω l^{'} = \frac{l}{2} A^{'} = 2 A R^{'} = ρ \frac{l^{'}}{A^{'}} = ρ \frac{\frac{l}{2}}{2 A} = \frac{1}{4} (ρ \frac{l}{A}) = \frac{1}{4} \times 8 = 2 Ω$

Q 20 :
Electrical resistivity of a given metallic wire depends upon:

its length
its thickness
its shape
nature of the material

1

2

3

4

(4)

The resistivity of a material is constant at a constant temperature. Resistivity of material does not depend on length, thickness, and shape of the material. It only depends on the temperature.

Topic Question Set

Q 11 :
The proper representation of series combination of cells for obtaining maximum potential is:

Q 12 :
The equivalent resistance of a series combination of two resistances is X ohm. If the resistances are of $10 Ω a n d 40 Ω$ respectively, the value of X will be:

Q 13 :
A cylindrical conductor of length l and uniform area of cross-section A has resistance R. The area of cross-section of another conductor of same material and same resistance but of length 2l is:

Q 14 :
The maximum resistance which can be made using four resistors each of resistance $\frac{1}{2} Ω$ is

Q 15 :
A piece of wire of resistance R is cut into five equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is R' then the ratio $\frac{R}{R'}$ is

Q 16 :
On which of the given factors, resistance does not depend:

Q 17 :
Which of the following obeys Ohm’s law?

Q 18 :
Electrical resistivity of an alloy of copper and nickel is _______ when compared with the electrical resistivity of an alloy of copper, manganese and nickel.

Q 19 :
There is a dual of 8 ohm resistance on the aerial. Determine the aerial’s new resistance.

Q 20 :
Electrical resistivity of a given metallic wire depends upon:

Want Us to Email you About Special Offers & Updates?

Topic Question Set

Q 11 : The proper representation of series combination of cells for obtaining maximum potential is:

Q 12 : The equivalent resistance of a series combination of two resistances is X ohm. If the resistances are of 10 Ω and 40 Ω respectively, the value of X will be:

Q 13 : A cylindrical conductor of length l and uniform area of cross-section A has resistance R. The area of cross-section of another conductor of same material and same resistance but of length 2l is:

Q 14 : The maximum resistance which can be made using four resistors each of resistance 12Ω is

Q 15 : A piece of wire of resistance R is cut into five equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is R' then the ratio RR' is

Q 16 : On which of the given factors, resistance does not depend:

Q 17 : Which of the following obeys Ohm’s law?

Q 18 : Electrical resistivity of an alloy of copper and nickel is _______ when compared with the electrical resistivity of an alloy of copper, manganese and nickel.

Q 19 : There is a dual of 8 ohm resistance on the aerial. Determine the aerial’s new resistance.

Q 20 : Electrical resistivity of a given metallic wire depends upon:

Want Us to Email you About Special Offers & Updates?

Q 11 :
The proper representation of series combination of cells for obtaining maximum potential is:

Q 12 :
The equivalent resistance of a series combination of two resistances is X ohm. If the resistances are of $10 Ω a n d 40 Ω$ respectively, the value of X will be:

Q 13 :
A cylindrical conductor of length l and uniform area of cross-section A has resistance R. The area of cross-section of another conductor of same material and same resistance but of length 2l is:

Q 14 :
The maximum resistance which can be made using four resistors each of resistance $\frac{1}{2} Ω$ is

Q 15 :
A piece of wire of resistance R is cut into five equal parts. These parts are then connected in parallel. If the equivalent resistance of this combination is R' then the ratio $\frac{R}{R'}$ is

Q 16 :
On which of the given factors, resistance does not depend:

Q 17 :
Which of the following obeys Ohm’s law?

Q 18 :
Electrical resistivity of an alloy of copper and nickel is _______ when compared with the electrical resistivity of an alloy of copper, manganese and nickel.

Q 19 :
There is a dual of 8 ohm resistance on the aerial. Determine the aerial’s new resistance.

Q 20 :
Electrical resistivity of a given metallic wire depends upon: