A hollow sphere of radius R, a hollow cube of side R and a thin circular plate of radius R, made up of the same material, are all heated to 200C above room temperature. When left to cool in the room, which of them will reach the room temperature first ?
An air bubble in water will act like a:
Consider the following statements:
I. A flute of smaller length produces waves of lower frequency.
II. Sound travels in rocks in the form of longitudinal elastic waves only.
Which of the statements given above is/are correct ?
Consider the following statements regarding a motor car battery:
I. The voltage is usually 12 V.
II. Electrolyte used is hydrochloric acid.
III. Electrodes are lead and copper.
IV. Capacity is expressed in ampere-hour.
Which of the above statements are correct ?
With reference to ‘fuel cells’ in which hydrogen-rich fuel and oxygen are used to generate electricity. Consider the following statements:
I. If pure hydrogen is used as a fuel, the fuel cell emits heat and water as by- products.
II. Fuel cells can be used for powering buildings and not for small devices like laptop computers.
III. Fuel cells produce electricity in the form of Alternating Current (AC).
IV. Which of the statements given about is/are correct?
Which of the statements given about is/are correct ?
Which of the following types is used by computed tomography employed for visualisation of the internal structure of human body ?
Consider the following statements: In a nuclear reactor, self- sustained chain reaction is possible, because:
I. more neutrons are released in each of the fission reactions.
II. the neutrons immediately take part in the fission process.
III. the fast neutrons are slowed down by graphite.
IV. every neutron released in the fission reaction initiates further fission.
Which of these statements are correct ?
Rainbow is produced when sunlight falls on drops of rain. Which of the following physical phenomena are responsible for this ?
III. Internal reflection
Select the correct answer using the codes below.
A simple machine helps a person in doing:
A ball is dropped from the top of a high building with a constant acceleration of 9.8 m/s2. What will be its velocity after 2 seconds ?