EdgineerX

1551. In an ideal transformer, the quantity that is the same in the primary and secondary is the

A. current B. voltage C. resistance D. number of turns E. power

1552. An induction furnace melts metal by means of

A. chemical reaction B. friction C. radiation from a filament D. heat generated by eddy currents induced in the charge E. conduction from a flame

1553. The direction of an induced current is such that its magnetic effect

A. reverses the magnet polarity permanently B. is perpendicular to the flux C. is zero D. assists the flux change producing it E. opposes the flux change producing it

1554. In order of increasing wavelength, the correct sequence is

A. visible, X-rays, gamma rays, radio waves B. gamma rays, X-rays, visible, radio waves C. radio waves, visible, X-rays, gamma rays D. infrared, visible, radio waves, gamma rays E. radio waves, infrared, visible, X-rays

1555. A device that converts direct current into alternating current is called

A. a transformer B. a filter C. an inverter D. an amplifier E. a rectifier

1556. An alternating voltage has an rms value of 220 V. Its peak value is about

A. 156 V B. 220 V C. 110 V D. 311 V E. 440 V

1557. The stress beyond which a material no longer returns to its original shape is the

A. elastic limit B. breaking stress C. ultimate tensile stress D. yield strain E. shear stress

1558. A ferromagnetic material owes its strong magnetism to

A. the alignment of magnetic domains B. lattice vibrations C. nuclear spin D. its high density E. free electrons only

1559. A transistor used as a switch operates between

A. reverse and forward breakdown B. cut off and saturation C. saturation and breakdown D. the active region and cut off E. two active points

1560. Besides NAND, the other gate that is universal is

A. XOR B. OR C. AND D. NOT E. NOR

1561. A capacitor placed across the output of a rectifier acts as

A. a switch B. an oscillator C. an amplifier D. a smoothing filter E. a rectifier

1562. According to special relativity, the mass of a body moving at speed comparable to that of light

A. decreases B. remains unchanged C. increases D. becomes zero E. becomes negative

1563. An electron microscope achieves higher resolution than an optical microscope because electrons have

A. a much shorter de Broglie wavelength B. a larger amplitude C. a lower speed D. no charge E. greater mass

1564. The value of Planck's constant is about

A. 1.6 x 10^-19 J s B. 6.63 x 10^-34 J s C. 6.63 x 10^-27 J s D. 9.1 x 10^-31 J s E. 3 x 10^8 J s

1565. A major limitation of Bohr's model is that it

A. requires quantized angular momentum B. predicts continuous spectra C. ignores the nucleus D. cannot account for the spectra of multi-electron atoms or fine structure E. explains the hydrogen spectrum

1566. X-rays are used in industry chiefly for

A. generating electricity B. cooling engines C. welding metals D. measuring temperature E. detecting flaws and cracks inside castings

1567. The wavelength of a spectral line is related to the wave number by

A. wave number equals c times the wavelength B. wave number equals h divided by the wavelength C. wave number equals the reciprocal of the wavelength D. wave number equals the wavelength E. wave number equals the wavelength squared

1568. The radius of a nucleus is of the order of

A. 10^-20 m B. 10^-10 m C. 10^-15 m D. 10^-6 m E. 10^-3 m

1569. A Geiger Muller counter detects radiation by

A. photographing the track B. registering the ionization pulse produced in a gas C. measuring the magnetic deflection D. weighing the sample E. measuring the temperature rise

1570. The most effective general precaution against exposure to ionizing radiation is to

A. hold the source in the hand B. use a stronger source C. increase the exposure time D. work without monitoring E. maximize the distance and use suitable shielding

1571. Fusion of deuterium nuclei in the laboratory is difficult mainly because of

A. the scarcity of deuterium B. the very high temperature and confinement needed C. the large mass of deuterium D. the weak nuclear force E. the absence of neutrons

1572. A radioactive tracer used to study thyroid function is an isotope of

A. carbon B. potassium C. cobalt D. iodine E. uranium

1573. The SI prefix representing a factor of 10^-12 is

A. nano B. pico C. femto D. milli E. micro

1574. The supplementary SI unit of solid angle is the

A. hertz B. radian C. steradian D. degree E. gradian

1575. When two quantities are divided, the percentage uncertainties are

A. squared B. subtracted C. multiplied D. added E. divided

Physics