Ray Optics and Optical Instruments — Physics STD 12 Science — Question

Two non-ideal batteries are connected in parallel. Consider the following statements:

1. The equivalent emf is smaller than either of the two emfs.
2. The equivalent internal resistance is smaller than either of the two internal resistances.

1. Both A and B are correct.
2. A is correct but B is wrong.
3. B is correct but A is wrong.
4. Both A and B are wrong.

Which of the following devices can be used as a square law device for modulation.

What transition He⁺ in ion shall have the same wave number as the first line:
in Balmer series of hydrogen atom?

Positive electric flux indicates that electric lines of force are directed:

The time period of rotation of the sun is 25 days and its radius is 7 . The Doppler shift for the light of wavelength 6000 Å emitted from the surface of the sun will be

(a) 0.04 Å

(b) 0.40 Å

(c) 4.00 Å

(d) 40.0 Å

The earth's magnetic field at a certain place has a horizontal component 0.3 Gauss and the total strength 0.5 Gauss. The angle of dip is

(a)

(b)

(c)

(d)

The mass of a particle is 400 times than that of an electron and the charge is double. The particle is accelerated by 5 V. Initially the particle remained in rest, then its final kinetic energy will be

(a) 5 eV

(b) 10 eV

(c) 100 eV

(d) 2000 eV

Biological importance of Ozone layer is 

(a) It stops ultraviolet rays

(b) Ozone rays reduce green house effect

(c) Ozone layer reflects radio waves

(d) Ozone layer controls   radio in atmosphere

In a sample of radioactive material, what fraction of the initial number of active nuclei will remain undisintegrated after half of a half-life of the sample

(a)

(b)

(c)

(d) 2