Physics

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Showing 376 to 400 of 1648 questions (page 16 of 66).

376. The energy equivalent of mass m is

A. mc B. mc2 C. m/c2 D. (1/2)mc2 E. m2c

377. Photoemission does not occur if the incident light has a frequency below the

A. cut off wavelength B. threshold frequency C. stopping potential D. Compton frequency E. Rydberg frequency

378. The wave nature of electrons was confirmed experimentally by

A. Millikan's oil drop experiment B. the Davisson and Germer electron diffraction experiment C. Rutherford's scattering experiment D. the photoelectric experiment E. Michelson's interferometer

379. The momentum of a photon of wavelength lambda is

A. h lambda B. h/lambda C. lambda/h D. hc/lambda E. h/c lambda

380. The work function of a metal is commonly expressed in

A. joules only B. electron volts C. watts D. coulombs E. hertz

381. The Lyman series of hydrogen lies in the

A. visible region B. ultraviolet region C. infrared region D. microwave region E. X-ray region

382. The energy of the electron in the second Bohr orbit of hydrogen is

A. -13.6 eV B. -6.8 eV C. -3.4 eV D. -1.51 eV E. -0.85 eV

383. In alpha decay, the mass number and atomic number of the nucleus change by

A. -4 and -2 B. -2 and -4 C. -4 and +2 D. 0 and -1 E. -1 and 0

384. The SI unit of radioactive activity is

A. curie B. becquerel C. gray D. sievert E. roentgen

385. Radiocarbon dating of organic remains uses the isotope

A. carbon 12 B. carbon 13 C. carbon 14 D. uranium 238 E. potassium 40

386. Nuclear forces are

A. long range and charge dependent B. short range and charge independent C. identical to electrostatic forces D. weaker than gravitational forces E. effective only between protons

387. The minimum mass of fissile material required to sustain a chain reaction is called the

A. atomic mass B. critical mass C. mass defect D. binding mass E. threshold mass

388. Cobalt 60 is used in medicine mainly as a source of

A. alpha particles B. beta particles C. gamma rays for radiotherapy D. neutrons E. X-rays

389. A radioactive sample of initial activity A0 has a half life T. Its activity after time 4T is

A. A0/4 B. A0/8 C. A0/16 D. A0/32 E. A0/2

390. How many base units are defined in the International System of Units (SI)?

A. 5 B. 8 C. 9 D. 7 E. 6

391. The dimensions of Planck's constant are the same as those of

A. angular momentum B. energy C. force D. power E. linear momentum

392. A screw gauge has a pitch of 0.5 mm and 50 divisions on its circular scale. Its least count is

A. 0.5 mm B. 0.01 mm C. 0.001 mm D. 0.025 mm E. 0.05 mm

393. Which of the following is a supplementary unit in SI?

A. mole B. joule C. kelvin D. newton E. radian

394. The dimensional formula of pressure is

A. [MLT-2] B. [ML-3T0] C. [ML-1T-2] D. [ML-2T-2] E. [ML2T-2]

395. If a quantity is measured as 4.0 cm with an absolute uncertainty of 0.1 cm, the percentage uncertainty is

A. 0.25% B. 0.4% C. 25% D. 2.5% E. 4%

396. A dimensionally correct equation

A. always contains a trigonometric term B. may still be physically incorrect C. is always physically correct D. cannot contain constants E. must be numerically correct

397. A unit vector perpendicular to the plane containing vectors A and B is given by

A. (A x B)/|A x B| B. A - B C. A + B D. (A.B)/|A||B| E. A.B

398. The value of i . (j x k) is

A. -1 B. i C. j E. 1

399. Two forces of 10 N each act on a body with an angle of 120 degrees between them. The magnitude of the resultant is

A. 17.3 N B. 20 N C. 0 N D. 14.1 N E. 10 N

400. If A + B = A - B, then vector B must be

A. a null vector B. parallel to A C. equal to A D. perpendicular to A E. a unit vector

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