In a single slit diffraction experiment first minimum for red light (660 nm) coincides with first maximum of some other wavelength l'. The value of l' is
|
(a) 4400 Å |
(b) 6600 Å |
(c) 2000 Å |
(d) 3500 Å |
(a) 4400 Å
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An electron is moving with constant velocity along x - axis. If a uniform electric field is applied along y- axis, then its path in the x - y plane will be
|
(a) A straight line |
(b) A circle |
(c) A parabola |
(d) An ellipse |
Thermocouple is a device for the measurement of
|
(a) Absolute temperature of a metal |
|
(b) The temperature difference between two substances |
|
(c) The couple acting on a wire |
|
(d) Thermal conductivity of a substance |
A current of 5 ampere is flowing in a wire of length 1.5 metres. A force of 7.5 N acts on it when it is placed in a uniform magnetic field of 2 Tesla. The angle between the magnetic field and the direction of the current is
|
(a) 30° |
(b) 45° |
(c) 60° |
(d) 90° |
The focal length of a concave mirror is 50 cm. Where an object be placed so that its image is two times and inverted
|
(a) 75 cm |
(b) 72 cm |
(c) 63 cm |
(d) 50 cm |
An object is immersed in a fluid. In order that the object becomes invisible, it should
|
(a) Behave as a perfect reflector |
|
(b) Absorb all light falling on it |
|
(c) Have refractive index one |
|
(d) Have refractive index exactly matching with that of the surrounding fluid |