1
KCET 2021
MCQ (Single Correct Answer)
+1
-0

A copper wire of length $$1 \mathrm{~m}$$ and uniform cross-sectional area $$5 \times 10^{-7} \mathrm{~m}^2$$ carries a current of $$1 \mathrm{~A}$$. Assuming that, there are $$8 \times 10^{28}$$ free electrons per $$\mathrm{m}^3$$ in copper, how long will an electron take to drift from one end of the wire to the other?

A
$$0.8 \times 10^3 \mathrm{~s}$$
B
$$1.6 \times 10^3 \mathrm{~s}$$
C
$$3.2 \times 10^3 \mathrm{~s}$$
D
$$6.4 \times 10^3 \mathrm{~s}$$
2
KCET 2021
MCQ (Single Correct Answer)
+1
-0

Consider an electrical conductor connected across a potential difference $$V$$. Let $$\Delta q$$ be a small charge moving through it in time $$\Delta t$$. If $$I$$ is the electric current through it,

I. the kinetic energy of the charge increases by $$I V \Delta t$$.

II. the electric potential energy of the charge decreases by $$I V \Delta t$$.

III. the thermal energy of the conductor increases by $$I V \Delta t$$.

Choose the correct option.

A
Only I
B
I and II
C
I and III
D
II and III
3
KCET 2021
MCQ (Single Correct Answer)
+1
-0

A strong magnetic field is applied on a stationary electron. Then, the electron

A
moves in the direction of the field
B
moves in an opposite direction of the field
C
remains stationary
D
starts spinning
4
KCET 2021
MCQ (Single Correct Answer)
+1
-0

Two parallel wires in free space are $$10 \mathrm{~cm}$$ apart and each carries a current of $$10 \mathrm{~A}$$ in the same direction. The force exerted by one wire on the other [per unit length] is

A
$$2 \times 10^{-4} \mathrm{~Nm}^{-1}$$ [attractive]
B
$$2 \times 10^{-7} \mathrm{~Nm}^{-1}$$ [attractive]
C
$$2 \times 10^{-4} \mathrm{~Nm}^{-1}$$ [repulsive]
D
$$2 \times 10^{-7} \mathrm{~Nm}^{-1}$$ [repulsive]
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