Practice Physics gk - general science mcq Online Quiz (set-1) For All Competitive Exams
Q-1) An electric bulb of 100 watt is used for 4 hours. The unit of electric energy used is
(a)
(b)
(c)
(d)
Q-2) Which impurity is doped in Si to form n-type semiconductors?
(a)
(b)
(c)
(d)
Because As is pentavalent impurity.
Q-3) How many units of electricity will be consumed if you use a 60 watt electric bulb for 5 hours everyday for 30 days?
(a)
(b)
(c)
(d)
Q-4) Small drops of the same size are charged to V volts each. If n such drops coalesce to form a single large drop, its potential will be
(a)
(b)
(c)
(d)
Q-5) A wire of resistance 16 W is bent in the form of a circle. What is the effective resistance between diametrically opposite points?
(a)
(b)
(c)
(d)
Q-6) Consider the following statements regarding a motor car battery:
- The voltage is usually 12 V.
- Electrolyte used is hydrochloric acid.
- Electrodes are lead and copper.
- Capacity is expressed in ampere-hour.
Which of the above statements are correct?
(a)
(b)
(c)
(d)
Q-7) On charging by conduction, mass of a body may
(a)
(b)
(c)
(d)
On charging by conduction, body may gain mass, if it acquires negative charge. It may lose mass, if it acquires positive charge.
Q-8) If the conductivity of a semiconductor is only due to break up of the covalent bonds due to thermal excitation, then the semiconductor is called
(a)
(b)
(c)
(d)
Q-9) If the electrical resistance of a typical substance suddenly drops to zero then the substance is called
(a)
(b)
(c)
(d)
Q-10) Five bulbs each of 100 watt capacity in a tunnel are illuminated continuously for twenty hours. The consumption of electricity will be
(a)
(b)
(c)
(d)
Q-11) If a body is charged by rubbing it, its weight
(a)
(b)
(c)
(d)
The weight can be increased slightly, if it acquire negative charge & weight can be decreased slightly, if it acquires positive charge.
Q-12) What is the order of magnitude of electric resistance of the human body (dry) ?
(a)
(b)
(c)
(d)
Q-13) The filament of a halogen lamp is an alloy of
(a)
(b)
(c)
(d)
Q-14) A dynamo which is said to generate electricity actually acts as a
(a)
(b)
(c)
(d)
Q-15) An object is kept 5 cm in front of a concave mirror of focal length 15 cm. What will be the nature of the image?
(a)
(b)
(c)
(d)
Q-16) When an optician prescribes a – 5D lens, what does it mean?
(a)
(b)
(c)
(d)
Q-17) Regarding a semiconductor which one of the following is wrong?
(a)
(b)
(c)
(d)
At room temperature, few bonds breaks and electron hole pair generates inside the semiconductor.
Q-18) A fuse is used in mains electric supply as a safety device. Which one of the following statements about the fuse is correct?
(a)
(b)
(c)
(d)
Afuse is a type ofsacrificial overcurrent protection device. Its essential component is a metal wire or strip that melts when too much current flows.
Short circuit, overload or device failure is often the reason for excessive current.
The resistance of the element used in fuse generates heat due to the current flow. It has low melting point so that it melts when a short-circuit or overloading takes place.
Q-19) A coin in a beaker filled with water appears raised. This phenomenon occurs because of the property of
(a)
(b)
(c)
(d)
Q-20) Electric motors operating at low voltages tend to burn out because
(a)
(b)
(c)
(d)