Current Electricity Class 12 Physics MCQs Pdf
11. A Daniel cell is balanced on 125 cm length of a potentiometer wire. Now the cell
is short-circuited by a resistance 2 ohm and the balance is obtained at 100 cm. The
internal resistance of the Daniel cell is
(a) 0.5 ohm
(b) 1.5 ohm
(c) 1.25 ohm
(d) 4/5 ohm
Answer/Explanation
Answer:
Explaination: a
12. When there is an electric current through a conducting wire along its length,
then an electric field must exist
(a) outside the wire but normal to it.
(b) outside the wire but parallel to it.
(c) inside the wire but parallel to it.
(d) inside the wire but normal to it.
Answer/Explanation
Answer: c
Explaination:
(c) Electric field parallel to wire inside creates potential difference and
electrostic force on electrons.
13. Three resistors each of 2 ohm are connected together in a triangular shape. The
resistance between any two vertices will be
(a) 4/3 ohm
(b) 3/4 ohm
(c) 3 ohm
(d) 6 ohm
Answer/Explanation
Answer: a
Explaination:
(a) Equivalent resistance of the combination
14. From the graph between current I and voltage V shown below, identify the portion
corresponding to negative resistance
(a) AB
(b) BC
(c) CD
(d) DE
Answer/Explanation
Answer: c
Explaination:
(c) For portion CD slope of the curve is negative i.e. resistance be negative.
15. A battery consists of a variable number V of identical cells having internal
resistances connected in series. The terminals of battery are short circuited and
the current i is measured. Which of the graph below shows the relationship between i
and n?
Answer/Explanation
Answer: d
Explaination: (d) I = \(\frac{n E}{n r}=\frac{E}{r}\). current is independent of
n.
16. A charge is moving across a junction, then
(a) momentum will be conserved.
(b) momentum will not be conserved.
(c) at some places momenturii will be conserved and at some other places momentum
will not be conserved.
(d) none of these.
Answer
Answer: d
17. Which of the following I-V graph represents ohmic conductors?
Answer
Answer: a
18. The I-V characteristics shown in figure represents
(a) ohmic conductors
(b) non-ohmic conductors
(c) insulators
(d) superconductors
Answer
Answer: b
19. Which of the following is correct for V-I graph of a good conductor?
Answer
Answer: a
20. The resistivity of alloy manganin is
(a) Nearly independent of temperature
(b) Increases rapidly with increase in temperature
(c) Decreases with increase in temperature
(d) Increases rapidly with decrease in temperature
Answer
Answer: a