1. Sound of frequency below 20 Hz is called
a) audio sounds
b) infrasonic
c) ultrasonic
d) supersonics
Explanation: Sound of frequency below 20 Hz is called Infrasonic.
2. On a clean glass plate a drop of water spreads to form a thin layer whereas a drop of mercury remains almost spherical because:
a) mercury is a metal.
b) density of mercury is greater than that of water.
c) cohesion of mercury is greater than its adhesion with glass.
d) cohesion of water is greater than its adhesion with glass.
Explanation: On a clean glass plate a drop of water spreads to form a thin layer whereas a drop of mercury remains almost spherical because cohesion of mercury is greater than its adhesion with glass.
3. Suitable impurities are added to a semiconductor depending on its use. This is done in order to
a) increase its life
b) enable it to withstand higher voltages
c) increase its electrical conductivity
d) increase its electrical resistivity
Explanation: Suitable impurities are added to a semiconductor depending on its use. This is done in order to increase its electrical conductivity.
4. Stars twinkle because
a) the intensity of light emitted by them changes with time.
b) the distance of the stars from the earth changes with time.
c) the refractive index of the different layers of the earth's atmosphere changes continuously.
d) None of these
Explanation: Stars twinkle because the refractive index of the different layers of the earth's atmosphere changes continuously.
5.It takes much longer to cook food in the hills than in the plains, because
a) in the hills the atmospheric pressure is lower than that in the plains and therefore water boils at a temperature lower than 100oC causing an increase in cooking time
b) due to low atmospheric pressure on the hills, the water boils at a temperature higher than 100oC and therefore water takes longer to boil
c) in the hills the atmospheric density is low and therefore a lot of heat is lost to the atmosphere
d) in the hills the humidity is high and therefore a lot of heat is absorbed by the atmosphere leaving very little heat for cooking
Explanation: It takes much longer to cook food in the hills than in the plains, because in the hills the atmospheric pressure is lower than that in the plains and therefore water boils at a temperature lower than 100oC causing an increase in cooking time.
6. ML2T-2 is the dimensional formula for
a) moment of inertia
b) pressure
c) elasticity
d) couple acting on a body
Explanation: ML2T-2 is the dimensional formula for couple acting on a body.
7. Solar eclipse will take place when
a) the sun is between the moon and the earth
b) the earth is between the moon and the sun
c) the moon is between the sun and the earth
d) the moon does not lie on the line joining the sun and the earth
Explanation: Solar eclipse will take place when the moon is between the sun and the earth.
8. Isotopes of an element contain
a) the same number of protons but different number of neutrons
b) the same number of neutrons but different number of protons
c) equal number of protons and electrons
d) equal number of nucleons
Explanation: Isotopes are atoms of the same element that have different numbers of neutrons but the same number of protons and electrons. The difference in the number of neutrons between the various isotopes of an element means that the various isotopes have different masses.
9. One watt-hour is equivalent to
a) 6.3 x 103 J
b) 6.3 x 10-7 J
c) 3.6 x 103 J
d) 3.6 x 10-3 J
Explanation: One watt-hour is equivalent to 3.6 x 103 J
10. Sir C.V. Raman was awarded Nobel Prize for his work connected with which of the following phenomenon of radiation?
a) Scattering
b) Diffraction
c) Interference
d) Polarization
Explanation: The Nobel Prize in Physics 1930 was awarded to Sir Chandrasekhara Venkata Raman "for his work on the scattering of light and for the discovery of the effect named after him."