1. | gamma rays, ultraviolet, infrared, microwaves. |
2. | microwaves, gamma rays, infrared, ultraviolet. |
3. | infrared, microwave, ultraviolet, gamma rays. |
4. | microwave, infrared, ultraviolet, gamma rays. |
Which colour of the light has the longest wavelength?
1. | violet | 2. | red |
3. | blue | 4. | green |
The energy of the EM waves is of the order of \(15~\mathrm{keV}\). To which part of the spectrum does it belong?
1. X-rays
2. Infrared rays
3. Ultraviolet rays
4. \(\gamma\)-rays
Out of the following options which one can be used to produce a propagating electromagnetic wave?
1. | a stationary charge. |
2. | a chargeless particle. |
3. | an accelerating charge. |
4. | a charge moving at constant velocity. |
1. | Ultraviolet rays | 2. | \(X\)-rays |
3. | Gamma-rays | 4. | Microwaves |
1. | \( b>a>c \) | 2. | \( a>b>c \) |
3. | \( c>b>a \) | 4. | \( a>c>b\) |
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. | \( 2.16~\text{cm}, 24.1~\text{GHz} \) | 2. | \( 0.29~\text{cm}, 13.7~\text{GHz} \) |
3. | \( 3.23 ~\text{cm}, 20.0~\text{GHz} \) | 4. | \( 1.26~\text{cm}, 23.9~\text{GHz}\) |
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. | \( 4.2 ~\text{V/m}, ~3.4 \times 10^{-6}~\text{T}\) |