Ohm's Law in Scalar Form

Q.
In the circuit shown in figure, find the value of R(in $\Omega$), so that the current through $15$ volts
battery is zero

Q. From the graph between current i & voltage V shown, identify the portion corresponding to negative resistance

1. BC
2. AB
3. CD
4. DE

Q.

When a potential difference of 2V is applied across a resistor, you observed a current I. When the length of the resistor is doubled without changing the thickness, what is the current observed when 2V is applied across it.

1. I

2. I/2

3. 2I

4. 4I

Q. The V-i graph for a conductor at temperature $T_1$ and $T_2$ are as shown in the figure. $(T_2-T_1)$ is proportional to

1. $cos2\theta$
2. $sin\theta$
3. $cot2\theta$
4. $tan\theta$

Q. Which of the circuits shown in figure can be used to verify Ohm’s law?

1. a
2. c
3. d
4. b

Q. Two wires of the same material having lengths in the ratio 2:3, are connected in series. The potential differences across the wires are 4.2V and 3.6V respectively. The ratio of their radii would be:

1. $2:\sqrt{7}$
2. $2:7$
3. $\sqrt{7}:2$
4. $7:2$

Q. In the following circuit diagram fig. the lengths of the wires AB and BC are same but the radius of AB is three times that of BC. The ratio of potential gradients at AB and BC will be

1. 1 : 9
2. 9 : 1
3. 3 : 1
4. 1 : 3

Q. Equal potentials are applied on an iron and copper wire of same length. In order to have same current flow in the wire, the ratio $\left(\frac{r_{iron}}{r_{copper}}\right)$ of their radii must be [ Given that specific resistance of iron $=1.0\times {10}^{-7}\Omega m$ and that of copper $=1.7\times {10}^{-8}\Omega m$ ]

1. About 2.4
2. About 1.2
3. About 3.6
4. About 4.8

Q. As the switch S is closed in the circuit shown in figure, current passed through it is

1. Zero
2. 1A
3. 2A
4. 1.6A

Q.

Figure represents a part of the closed circuit. If a current of 2A flows in from A, the potential difference between points A and B, $V_A-V_B$ is:

1. + 9 V
2. – 9 V
3. + 6 V
4. + 3 V