Hi-profile Questions from Physics

A chamber contains a mixture of helium and hydrogen gas. The ratio of rms of He to that of H₂molecules will be
a. 2
b. 1.414
c. 0.72
d. 0.5

A soap film held vertically is viewed in reflected sunlight. The observer would see a number of
a. horizontal colored fringes
b. vertical white and black fringes
c. horizontal white and black fringes
d. vertical colored fringes
A sample contains 10 mg of radio-active materials of half-life 270 days. After 540 days, the mass of radio-active materials left will be in mg
a. 5
b. 2.5
c. 1.25
d. 0
The ferromagnetic substance is converted into paramagnetic substance
a. below the Curie temperature
b. at the Curie temperature
c. above the Curie temperature
d. at the absolute zero
In order to increase the frequency of transverse oscillations of a stretched wire by 50%, its tension must be increased by
a. 100%
b. 150%
c. 125%
d. 50%
The electric conductivity of a pure Silicon sample can be increased by
a. increasing the temperature
b. doping it with acceptor impurity
c. doping it with donor impurity
d. shining ultraviolet light on it
A bucket containing water is rotated in a vertical circle. The water does not fall out of the bucket even when it is at the top, because:
a. weight of water is zero
b. sufficient time is not available for the fall
c. inertia prevents it from falling
d. cohesive forces do not allow it to fall
The heat produced by a 100 W heater in 2 minutes is equal to
a. 200 K Cal
b. 100 K Cal
c. 50 K Cal
d. 25 K Cal
A man swimming under water looks at yellow colored object outside. What will be the colour of the object as seen by the man under the water surface?
a. red
b. yellow
c. green
d. white
The Kinetic Energy of a particle becomes 4 times. How many times will its de-Broglie wavelength be?
a. 1/4
b. 1/2
c. 2
d. 4
Electric power is transmitted over long distances at high voltage because
a. current thru live wire is large
b. potential drop is large
c. heat produced in live wire is large
d. heat produced in live wire is small