Physics M.C.Q (1 Marks)

2. Decrease in resistivity.

1. $\text{R}=\text{r}$

1. The charge crossing in a given time interval.

4. Free-electron density.

2. Increase.

1. No change.

2. Thermistor.

3. 0.114A

4. Red

3. Increase.

4. The difference between the emf of a cell and potential difference across the ends of the cell is called lost volts.

Insulators are materials which do not conduct electric current, and thereby, offer high resistance to the flow of charges. Insulators like bakelite and hard rubber have very high resistivities in the range of $10^{14}$ to $10^{16} \Omega m.$

1. The charge on $C$ long after $t = 0$ is $\epsilon\text{C}.$
2. The current in $L$ just before $t = t_{0}$ is $\frac{\epsilon}{\text{R}}.$

4. None of these.

2. Errors of measurement do depend on the accuracy with which $R_2$ and $R_1$ can be measured.
3. If the student uses large values of $R_2$ and $R_1,$ the currents through the arms will be feeble.
4. This will make determination of null point accurately more difficult.
5. According to the question, for first student $, R_2 = 10\Omega, R_1 = 5\Omega, R_3 = 5\Omega$
   For second student $,R_1 = 500\Omega, R_3 = 5\Omega$
   For balanced wheatstone bridge,
   $\frac{\text{R}_2}{\text{R}}=\frac{\text{R}_1}{\text{R}_3}$
6. $\Rightarrow\ \text{R}=\text{R}_3\times\Big(\frac{\text{R}_1}{\text{R}_2}\Big)$
   Putting values in above relation, we will find that value of $R$ for both the students comes out to be $10\Omega .$
   The errors of measurement of the two students depend on the accuracy and sensitivity of the bridge, which in turn depends on the accuracy with which $R_2$ and $R_1$ can be me asured.

2. The straight-line V-I graph pass through the origin.

2. Rate of Joule heating if the same current goes through them.

4. Time constant if one solenoid is connected to one battery and the other is connected to another battery.

3. $\text{R}=\text{r}$

4. Drift velocity decreases with the increasing length of conductor.

3. $\Omega1$

1. The meter bridge can have no other neutral point for this set of resistances.

3. When the jockey contacts a point on the meter wire to the right of D, current flows from B to the wire through galvanometer.

1. Increases.

2. $\sqrt{\text{V}}$

2. The currents in the two discharging circuits at $t = 0$ are equal but not zero.

4. $C_1$ loses $50\%$ of its initial charge sooner than $C_2$ loses $50\%$ of its initial charge.

1. 5s
2. 50s
3. 500s
4. 500s

2. Electric field produced by charges accumulated on the surface of wire.

1. Number of charge carriers can change with temperature T.
2. Time interval between two successive collisions can depend on T.

1. Maximum when the battery is connected across $1\text{cm}\times\frac{1}{2}\text{cm}$ faces.

1. $2\Omega$

2. 2 : 1

3. One joule per second.

1. $\frac{1}{\text{RC}}$
2. $\frac{\text{R}}{\text{L}}$
3. $\frac{1}{\sqrt{\text{LC}}}$

3. B is correct but A is wrong.

1. Both A and B are correct.