In the adjacent diagram, CP represents a wavefront and AO & BP, the corresponding two rays. Find the condition on q for constructive interference at P between the ray BP and reflected ray OP
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(a) cosq = 3l/2d |
(b) cosq = l/4d |
(c) secq – cosq = l/d |
(d) secq – cosq = 4l/d |
(b) cosq = l/4d
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A film projector magnifies a 100 cm2 film strip on a screen. If the linear magnification is 4, the area of magnified film on the screen is
|
(a) 1600 cm2 |
(b) 400 cm2 |
(c) 800 cm2 |
(d) 200 cm2 |
The phase difference between incident wave and reflected wave is 180° when light ray
|
(a) Enters into glass from air |
(b) Enters into air from glass |
|
(c) Enters into glass from diamond |
(d) Enters into water from glass |
Two insulated charged conducting spheres of radii 20 cm and 15 cm respectively and having an equal charge of 10 C are connected by a copper wire and then they are separated. Then
|
(a) Both the spheres will have the same charge of 10 C |
|
(b) Surface charge density on the 20 cm sphere will be greater than that on the 15 cm sphere |
|
(c) Surface charge density on the 15 cm sphere will be greater than that on the 20 cm sphere |
|
(d) Surface charge density on the two spheres will be equal |
The electron emitted in beta radiation originates from
|
(a) Inner orbits of atoms |
(b) Free electrons existing in nuclei |
|
(c) Decay of a neutron in a nucleus |
(d) Photon escaping from the nucleus |
A convex mirror of focal length f forms an image which is 
times the object. The distance of the object from the mirror is
|
(a) (n – 1)f |
(b) |
(c) |
(d) (n + 1)f |
X-rays when incident on a meta
|
(a) Exert a force on it |
(b) Transfer energy to it |
|
(c) Transfer pressure to it |
(d) All of the above |
electrons reach the anode per second. If the power consumed is 448 milliwatts, then the plate (anode) voltage is
|
(a) 150 V |
(b) 200V |
(c) 14 × 448 V |
(d) 448/14V |
