MCQs

Q281: A man throws a ball vertically upwards in compartment of an accelerated train. The ball will fall _______?

• A) In his hand
• B) In front of him
• C) Behind him

Q282: Two glass prisms P1 and P2 are to be combined together to produce dispersion without deviation. The angle of the prisms P1 and P2 are selected as 40 and 30 respectively. If the refractive index of prism P1 is 1.54, then that of P2 will be _____?

• A) 1.48
• B) 1.62
• C) 1.72

Q283: A ball is thrown vertically upward with a velocity of 98 m/s if it takes 10 seconds to reach the highest point then the acceleration of the ball is _____?

• A) 9.8 m/s²
• B) 98 m/s²
• C) 980 m/s²

Q284: A bar magnet of magnetic moment 200 A − m² is suspended in a magnetic field of intensity 0.25 N/A − m. The couple required to deflect it through 30° is _____?

• A) 15 N − m
• B) 50 N − m
• C) 25 N − m

Q285: An electric cell of e.m.f E is connected across a copper wire of diameter d and length l. The drift velocity of electrons in the wire is vd. If the length of the wire is changed to 2l, the new drift velocity of electrons in the copper wire will be _____?

• A) vd/2
• B) vd/3
• C) vd/4

Q286: A frictionless piston-cylinder based enclosure contains some amount of gas at a pressure of 400 kPa. Then heat is transferred to the gas at constant pressure in a quasi-static process. The piston moves up slowly through a height of 10 cm. If the piston has a cross-sectional area of 0.3m², the work done by the gas in this process is _____?

• A) 24kj
• B) 6kj
• C) 12kj

Q287: The R.M.S. speed of a molecules of a gas at A 100 degree centigrade is v. the temperature at which the R.M.S speed will be 3v is ______?

• A) 746 degree centigrade
• B) 546 degree centigrade
• C) 3084 degree centigrade

Q288: A body when fully immersed in a liquid of specific gravity 1.2 weighs 44 gwt. The same body when fully immersed in water weighs 50 gwt. The mass of the body is?

• A) 80 g
• B) 64 g
• C) 36 g

Q289: A magnetic needle is placed in a uniform magnetic field and is aligned with the field. The needle is now rotated by an angle of 60° and the work done is W. The torque on the magnetic needle at this position is _____?

• A) (3/2)W
• B) 2V3W
• C) √3W

Q290: Two radioactive substances A and B have decay constants 5λ and λ, respectively. At t = 0, a sample has the same number of the two nuclei. The time taken for the ratio of the number of nuclei to become (1/e)2 will be ______?

• A) 1/2λ
• B) 1/3λ
• C) 1/4λ