1. | \(E_z=60 \sin \left(0.5 \times 10^3 x+1.5 \times 10^{11} t\right) ~\text{V/m} \) |
2. | \(E_z=60 \sin \left(1.5 \times 10^3 x+0.5 \times 10^{11} t\right) ~\text{V/m} \) |
3. | \(E_z=55 \sin \left(0.5 \times 10^3 x+1.5 \times 10^{11} t\right) ~\text{V/m} \) |
4. | \(E_z=55 \sin \left(1.5 \times 10^3 x+0.5 \times 10^{11} t\right) ~\text{V/m} \) |
Assume a bulb of efficiency \(2.5\%\) as a point source. The peak values of the electric field and magnetic field produced by the radiation coming from a \(100~\text{W}\) bulb at a distance of \(3~\text{m}\) are respectively:
1. | \( 2.5 ~\text{V/m}, ~2.2 \times 10^{-8} ~\text{T} \) |
2. | \( 3.6 ~\text{V/m}, ~ 3.6 ~\text{T} \) |
3. | \( 4.07~\text{V/m},~ 1.4 \times 10^{-8} ~\text{T}\) |
4. | \( 4.2 ~\text{V/m}, ~3.4 \times 10^{-6}~\text{T}\) |
A capacitor of capacitance \(C\) is connected across an AC source of voltage \(V\), given by;
\(V=V_0 \sin \omega t\)
The displacement current between the plates of the capacitor would then be given by:
1. \( I_d=\frac{V_0}{\omega C} \sin \omega t \)
2. \( I_d=V_0 \omega C \sin \omega t \)
3. \( I_d=V_0 \omega C \cos \omega t \)
4. \( I_d=\frac{V_0}{\omega C} \cos \omega t\)
1. | \( 2.16~\text{cm}, 24.1~\text{GHz} \) | 2. | \( 0.29~\text{cm}, 13.7~\text{GHz} \) |
3. | \( 3.23 ~\text{cm}, 20.0~\text{GHz} \) | 4. | \( 1.26~\text{cm}, 23.9~\text{GHz}\) |
The biological importance of the ozone layer is:
1. | it stops ultraviolet rays. |
2. | ozone layer reduces the greenhouse effect. |
3. | ozone layer reflects radio waves. |
4. | ozone layer controls \(\mathrm{O}_2 / \mathrm{H}_2\) ratio in the atmosphere. |
1. | \( b>a>c \) | 2. | \( a>b>c \) |
3. | \( c>b>a \) | 4. | \( a>c>b\) |
Statement I: | Charged particles which undergo acceleration or deceleration radiate their energy away. |
Statement II: | Therefore, charged particles moving in circular paths in a uniform magnetic field should also radiate their energy. |
1. | Statement I is true, Statement II is true and Statement I implies Statement II. |
2. | Statement I is true, Statement II is true and Statement I does not imply Statement II. |
3. | Statement I is true, Statement II is false. |
4. | Statement I is false, Statement II is true. |
The speed of light depends:
1. | on elasticity of the medium only. |
2. | on inertia of the medium only. |
3. | on elasticity as well as inertia. |
4. | neither on elasticity nor on inertia. |
A compass needle is placed in the gap of a parallel plate capacitor. The capacitor is connected to a battery through a resistance. The compass needle:
1. | does not deflect. |
2. | deflects for a very short time and then comes back to the original position. |
3. | deflects and remains deflected as long as the battery is connected. |
4. | deflects and gradually comes to the original position in a time which is large compared to the time constant. |
Displacement current goes through the gap between the plates of a capacitor when the charge of the capacitor:
(a) | increases |
(b) | decreases |
(c) | does not change |
(d) | is zero |