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 2020
MCQ (Single Correct Answer)
+1
-0

A metal rod of length $$10 \mathrm{~cm}$$ and a rectangular cross-section of $$1 \mathrm{~cm} \times \frac{1}{2} \mathrm{~cm}$$ is connected to a battery across opposite faces. The resistance will be

A
maximum when the battery is connected across $$1 \mathrm{~cm} \times \frac{1}{2} \mathrm{~cm}$$ faces
B
maximum when the battery is connected across $$10 \mathrm{~cm} \times \frac{1}{2} \mathrm{~cm}$$ faces
C
maximum when the battery is connected across $$10 \mathrm{~cm} \times 1 \mathrm{~cm}$$ faces
D
same irrespective of the three faces
4
KCET 2020
MCQ (Single Correct Answer)
+1
-0

A car has a fresh storage battery of emf $$12 \mathrm{~V}$$ and internal resistance $$2 \times 10^{-2} \Omega$$. If the starter motor draws a current of $$80 \mathrm{~A}$$. Then, the terminal voltage when the starter is On is

A
12 V
B
8.5 V
C
8.4 V
D
9.3 V
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