How should people wearing spectacles work with a microscope
|
(a) They cannot use the microscope at all |
(b) They should keep on wearing their spectacles |
|
(c) They should take off spectacles |
(d) (b) and (c) is both way |
(c) They should take off spectacles
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Threshold frequency for a metal is 
Hz. Light of 
falls on its surface. Which of the following statements is correct
|
(a) No photoelectric emission takes place |
|
(b) Photo-electrons come out with zero speed |
|
(c) Photo-electrons come out with 103 m/sec speed |
|
(d) Photo-electrons come out with 105 m/sec speed |
When a metal surface is illuminated by light of wavelengths 400 nm and 250 nm, the maximum velocities of the photoelectrons ejected are v and 2v respectively. The work function of the metal is (h = Planck’s constant, c = velocity of light in air)
|
(a) 2hc |
(b) |
(c) |
(d) 0.5 |
Resistors of 1, 2, 3 ohm are connected in the form of a triangle. If a 1.5 volt cell of negligible internal resistance is connected across 3 ohm resistor, the current flowing through this resistance will be
|
(a) 0.25 amp |
(b) 0.5 amp |
(c) 1.0 amp |
(d) 1.5 amp |
A particle of mass m and charge q moves with a constant velocity v along the positive x direction. It enters a region containing a uniform magnetic field B directed along the negative z direction, extending from x = a to x = b. The minimum value of v required so that the particle can just enter the region x > b is
|
(a) qb B/m |
(b) q(b – a) B/m |
(c) qaB/m |
(d) q(b + a)B/2m |
