A weightless rubber balloon is filled with 200 cc of water. Its weight in water is equal to:
(a) 9.8/5 N
(b) 9.8/10 N
(c) 9.8/2 N
Since balloon is filled up with water & put into water, it is in stable position. The downward force exerted by it is equal to the upward buoyant force exerted by water. Hence, its weight in water is zero as the resultant force on it is zero.
What is the order of magnitude of electric resistance of the human body (dry)?
(a) 10^2 Ohm
(b) 10^4 ohm
(c) 10^6 ohm
(d) 10^8 ohm
Human body contains 70% of water, so it is good conductor, but if we measure body resistance by electronic-multimeter then the resistance is about 1 mega-ohm.
Assertion (A): In our houses, the current in A.C. electricity line changes direction 60 times per second.
Reason (R): The frequency of alternating voltage supplied is 50 Hz.
(a) Both A and R is true and R is the correct explanation of A.
(b) Both A and R is true but R is not the correct explanation of A.
(c) A is true but R is false
(d) A is false but R is true.
Assertion is not correct. An alternating voltage or current has two half cycles in one full cycle. Since frequency of A.C. voltage is 50 Hz or 50 cycles/sec, so in our houses the current in A.C. electricity line changes direction = 50 X 2 = 100 times per second.
An oil tanker is partially filled with oil and moves forward on a level road with uniform acceleration. The free surface of oil then:
(a) remains horizontal
(b) is inclined to the horizontal with smaller depth at the rear end
(c) is inclined to the horizontal with larger depth at the rear end
(d) assumes parabolic curve
An oil tanker is partially filled with oil and moves forward on a level road with uniform acceleration. The free surface of oil then is inclined to the horizontal with larger depth at the rear end.
Which one of the following does a TV remote control unit use to operate a TV set?
(a) Light waves
(b) Sound waves
(d) Radio waves
Radio waves are used to transmit radio and TV signals.
The memory of a computer is commonly expressed in terms of kilobytes or megabytes. A byte is made up of:
(a) eight binary digits
(b) eight binary digits
(c) two binary digits
(d) two decimal digits
The computer memory is expressed in kilobytes or megabytes or gigabytes. One byte is made of binary digits
1 bytes = 8 binary digits
A ‘black hole’ is a body in space which does not allow any radiation to come out. This property is due to its:
(a) very small size
(b) very large size
(c) very high density
(d) very low size
A black hole is a region space in which the gravitational force is so great that n object (Particles or light) can escape from it. Thus, it has very high density.
A noise level of 100 decibel would correspond to:
(a) Just audible sound
(b) Ordinary conversation
(c) Sound from a noisy street
(d) Noise from a machine shop
Loundness of sound is measured on the scale called the decibel scale. The softest audible sound on the decibel scale is zero db. The noise level of 100 decibel would correspond to noise from a machine shop.
For which one of the following is capillarity not the reason?
(a) Blotting of ink
(b) Rising of underground water
(c) Spread of water drop on a cotton cloth
(d) Rising of water from the roots of a plant to its foliage
Capillary is a hair like tube. It is found that when a capillary tube open at both ends is dipped in a liquid, the liquid rises up in the tube. The example of capillarity are blotting of ink, spread of water drop on a cotton cloth and rising of water from the roots of a plant to it’s foliage.
The working principle of a washing machine is:
(c) reverse osmosis
Washing machine works on the principle of centrifugation.