- AConverts light into electricity.
- BConverts electricity into light.
- CStores light.
- DStores electricity.
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
$\frac{1}{2}$
$2$
$\frac{1}{4}$
$4.$
A body of capacity 4μF is charged to 80 V and another body of capacity 6μF is charged to 30V. When they are connected the energy lost by 4 μF capacitor is
|
(a) 7.8 mJ |
(b) 4.6 mJ |
(c) 3.2 mJ |
(d) 2.5 mJ |
In producing a pure spectrum, the incident light is passed through a narrow slit placed in the focal plane of an achromatic lens because a narrow slit:
$\text{mgvt}\cos^2\theta$
$\text{mgvt}\sin^2\theta$
$\text{mgvt}\sin2\theta$
Assertion : The surface wave propagation is used for medium wave band and for television broadcasting.
Reason : The surface waves travel directly from transmitting antenna to receiver antenna through atmosphere.
|
(a) If both assertion and reason are true and the reason is the correct explanation of the assertion. |
|
(b) If both assertion and reason are true but reason is not the correct explanation of the assertion. |
|
(c) If assertion is true but reason is false. |
|
(d) If the assertion and reason both are false. |
Ultraviolet light of wavelength 300 nm and intensity 1.0 watt/m2 falls on the surface of a photosensitive material. If 1% of the incident photons produce photoelectrons, then the number of photoelectrons emitted from an area of 1.0 cm2 of the surface is nearly
|
(a) 9.61 |
(b) 4.12 |
|
(c) 1.51 |
(d) 2.13 |