The power of a biconvex lens is \(10\) dioptre and the radius of curvature of each surface is \(10\) cm. The refractive index of the material of the lens is:
| 1. | \( \dfrac{4}{3} \) | 2. | \( \dfrac{9}{8} \) |
| 3. | \( \dfrac{5}{3} \) | 4. | \( \dfrac{3}{2}\) |
An intrinsic semiconductor is converted into an \(\mathrm{n\text{-}}\)type extrinsic semiconductor by doping it with:
1. phosphorous
2. aluminium
3. silver
4. germanium
A barometer is constructed using a liquid (density = \(760~\text{kg/m}^3\)). What would be the height of the liquid column, when a mercury barometer reads \(76~\text{cm}?\)
(the density of mercury = \(13600~\text{kg/m}^3\))
| 1. | \(1.36~\text m\) | 2. | \(13.6~\text m\) |
| 3. | \(136~\text m\) | 4. | \(0.76~\text m\) |
| 1. | \( \dfrac{{IL}^2}{4} ~\text{A}\text-\text{m}^2 \) | 2. | \( \dfrac{{I} \times \pi {L}^2}{4} ~\text{A}\text-\text{m}^2 \) |
| 3. | \( \dfrac{2 {IL}^2}{\pi}~\text{A}\text-\text{m}^2 \) | 4. | \( \dfrac{{IL}^2}{4 \pi}~\text{A}\text-\text{m}^2 \) |
A parallel plate capacitor with cross-sectional area \(A\) and separation \(d\) has air between the plates. An insulating slab of the same area but the thickness of \(\dfrac{d}{2}\) is inserted between the plates as shown in the figure, having a dielectric constant, \(K=4.\) The ratio of the new capacitance to its original capacitance will be:
| 1. | \(2:1\) | 2. | \(8:5\) |
| 3. | \(6:5\) | 4. | \(4:1\) |
| 1. | \(\dfrac R {n^2}\) | 2. | \(\dfrac {R~(n-1)} n\) |
| 3. | \(\dfrac {Rn} { (n-1)}\) | 4. | \(\dfrac R n\) |
Time intervals measured by a clock give the following readings:
\(1.25~\text{s},~1.24~\text{s}, ~1.27~\text{s},~1.21~\text{s},~1.28~\text{s}.\)
What is the percentage relative error of the observations?
1. \(2\)%
2. \(4\)%
3. \(16\)%
4. \(1.6\)%
| 1. | \(2(\hat{i}+\hat{j})\) | 2. | \(\hat{i}+\hat{j}\) |
| 3. | \(\frac{2}{3}(\hat{i}+\hat{j})\) | 4. | \(\frac{4}{3}(\hat{i}+\hat{j})\) |
The equivalent resistance between \(A\) and \(B\) for the mesh shown in the figure is:
| 1. | \(7.2~\Omega\) | 2. | \(16~\Omega\) |
| 3. | \(30~\Omega\) | 4. | \(4.8~\Omega\) |
Calculate the acceleration of the block and trolly system shown in the figure. The coefficient of kinetic friction between the trolly and the surface is \(0.05.\)
( \(g=10~\text{m/s}^2,\) the mass of the string is negligible and no other friction exists)
| 1. | \( 1.25~\text{m/s}^2\) | 2. | \( 1.50~\text{m/s}^2\) |
| 3. | \(1.66~\text{m/s}^2\) | 4. | \( 1.00~\text{m/s}^2\) |
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