Electrostatic Potential and Capacitance — Physics STD 12 Science — Question

A direct current of 4 A is flowing through any circuit. Root mean square value of the current is:

Assertion :  In Young’s double slit experiment, the fringes become indistinct if one of the slits is covered with cellophane paper.
Reason     : The cellophane paper decrease the wavelength of light.(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.

Choose the correct answer from the alternatives given. Electromagnetic wave consists of periodically oscillating electric and magnetic vectors:

During the 19th century, light was considered to be a stream of particles called:

Is the ratio of frequencies of UV rays and IR rays in the glass more than, less than or equal to 1?

To an observer on the earth the stars appear to twinkle. This can be ascribed to(a) The fact that stars do not emit light continuously(b) Frequent absorption of star light by their own atmosphere(c) Frequent absorption of star light by the earth's atmosphere(d) The refractive index fluctuations in the earth's atmosphere

The sun emits a light with maximum wavelength 510 mm while another star X emits a light with maximum wavelength of 350 nm. What is the ratio of surface temperature of sun and the star X (a) 2.1(b) 0.68(c) 0.46(d) 1.45

A unitless quantity:

1. Never has a non-zero dimension.
2. Always has a non-zero dimension.
3. May have a non-zero dimension.
4. Does not exist.