41.

An electron of a stationary hydrogen atom passes from the fifth energy level to ground level. The velocity that the atom acquired as a result of photon emission will be

• 
• 
• 
• 

Two sources of sound placed close to each other, are emitting progressive waves given by
y₁ = 4sin 600π t and y₂ = 5 sin 608πt

An observer located near these two sources of sound will hear

•  4 beats per second  with intensity ratio 25: 16 between waxing and waning

• 8 beats per second with intensity ratio 25:16 between  waxing and waning

• 8 beats per second with intensity ratio 81:1 between waxing and waning

• 8 beats per second with intensity ratio 81:1 between waxing and waning

The magnifying power of a telescope is 9. When it is adjusted for parallel rays the distance between the objective and eyepiece is 20 cm. The focal length of lenses are

• 10 cm, 10 cm

• 15 cm, 5 cm

• 18 cm, 2cm

• 18 cm, 2cm

An α- particle moves in a circular path of radius 0.83 cm in the presence of a magnetic field of 0.25 Wb/m². The de-Broglie wavelength associated with the particle will be

• 1 A^o

• 0.1 A^o

• 10 A^o

• 10 A^o

Monochromatic radiation emitted when electron on hydrogen atom jumps from first excited to the ground state irradiates a photosensitive material. The stopping potential is measured to be 3.57 V. The threshold frequency of the material is

• 4 x 10¹⁵ Hz

• 5 x 10¹⁵ Hz

• 1.6 x10¹⁵ Hz

• 1.6 x10¹⁵ Hz

The figure shows a logic circuit with two inputs A and B and the output C. The voltage waveforms across A, B and C are as given. The logic circuit gate is

• OR Gate

• NOR Gate

• AND Gate

• AND Gate

Transfer characteristic [output voltage (V_o)  vs input voltage (V_i)] for a base biased transistor in CE configuration is as shown in the figure. For using transistor as a switch, it is used

• in region III

• both in region (I) and (III)

• in region (II)

• in region (II)

A concave mirror of focal length f₁ is placed at a distance of d from a convex lens of focal length f₂. A beam of light coming from infinity and falling on this convex lens concave mirror combination returns to infinity. The distance d must be equal

• f₁ +f₂

• -f₁ +f₂

• 2f₁+f₂

• 2f₁+f₂

A ray of light is incident at an angle of incidence, i, on one face of the prism of angle A (assumed to be small) and emerges normally from the opposite face. If the refractive index of the prism is u, the angle of incidence i, is nearly equal to

Two ideal diodes are connected to a battery as shown in the circuit. The current supplied by the battery is

• 0.75 A

• zero

• 0.25

• 0.25