Alternating Current — Physics STD 12 Science — Question

What type of nature do electromagnetic waves have?

 amp is flowing through a resistance of 1000Ω. To measure the correct potential difference, the voltmeter is to be used of which the resistance should be

(a) 0 Ω

(b) 500 Ω

(c) 1000 Ω

(d) >> 1000 Ω

The refractive index of water is 4 / 3 and that of glass is 5/3.  What will be the critical angle for the ray of light entering water from the glass  

(a)

(b)

(c)

(d)

In Bohr model of hydrogen atom, let P.E. represents potential energy and T.E. represents the total energy. In going to a higher level:

For nuclei with A > 100:

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

Wave nature of light follows because

(a) Light rays travel in a straight line

(b) Light exhibits the phenomena of reflection and refraction

(c) Light exhibits the phenomenon of interference

(d) Light causes the phenomenon of photoelectric effect

A circular coil of conducting wire has an area A and number of turns N. It is lying in a vertical plane in a region where uniform magnetic field B exist with field direction normal to the coil plane. If the coil is rotated about a vertical axis by an angle π in 0.5 seconds, then the value of the emf induced at the ends of the coil is.

A spherical condenser has inner and outer spheres of radii a and b respectively. The space between the two is filled with air. The difference between the capacities of two condensers formed when outer sphere is earthed and when inner sphere is earthed will be

(a) Zero

(b) 4π

(c)  4π

(d) 4 π

Consider a simple circuit shown in Fig. stands for a variable resistance R'. R' can vary from R₀ to infinity. r is internal resistance of the battery (r < < R < < R₀).