NCERT Solutions for class 12 Physics | Chapter 3 - Current Electricity
Questions
1
In a potentiometer of 10 wires, the balance point is obtained on the 7th wire. To shift the balance point to 9th wire, we should
Answer:increase resistance in series with the cell whose emf is to be determined.
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3
In the series combination of two or more than two resistances
Answer:the current through each resistance is same.
5
In a Wheatstone bridge if the battery and galvanometer are interchanged then the deflection in galvanometer will
Answer:not change
6
When a metal conductor connected to left gap of a meter bridge is heated, the balancing point
Answer:shifts towards right
7
An electric heater is connected to the voltage supply. After few seconds, current gets its steady value then its initial current will be
Answer:slightly higher than its steady current
8
The I-V characteristics shown in figure represents
Answer:non-ohmic conductors
9
AB is a wire of potentiometer with the increase in the value of resistance R, the shift in the balance point J will be
Answer:towards B
10
Combine three resistors 5 Q, 4.5 Q and 3 Q in such a way that the total resistance of this combination is maximum
Answer:12.5 Q
11
The resistivity of alloy manganin is
Answer:Nearly independent of temperature
12
If n cells each of emf e and internal resistance r are connected in parallel, then the total emf and internal resistance will be
A
B
ε,nr
C
D
nε, nr
Answer:
13
A cell having an emf E and internal resistance r is connected across a variable external resistance R. As the resistance R is increased, the plot of potential difference V across R is given by
A
B
C
D
Answer:
15
When the wires are connected in parallel, the heat produced in the thinner wire is H1 and that in the thicker wire is H2 Then:
Answer:H1 < H2
16
A wire P is half the diameter and half the length of a wire Q of similar material. The ratio of resistances of P to that 0 is:
Answer:2 : 1
17
In a Wheatstone bridge, the resistance each arm is 10 Ω. If the resistance galvanometers is also 10 Ω, then effective resistance of the bridge will be :
Answer:10 Ω
18
Two bulbs 25 W, 220 V and 100 W, 220 V are given. Which has higher resistance?
Answer:25 W
19
In India electricity is supplied fordomestic use at 220 V. It is supplied at 110 V in U.S.A. If the resistance of a 60 W bulb use in India is R. the resistance of a 60 W bulb for use in USA will be:
Answer:R/4
20
Which of the following has a negative temperature coefficient of resistance ?
Answer:Carbon
Chapters
- Electric Charges & Fields
- Electrostatic potential and capacitance
- Electricity
- Moving charges and magnetism
- Magnetism and matter
- Electromagnetic induction
- Alternating current
- Electromagnetic waves
- Ray optics and optical instruments
- Wave optics
- Dual nature of radiation and matter
- Atoms
- Nuclei
- Semiconductor electronics
- Communication systems
