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The stream of a river is flowing with a speed of 2 km/h. A swimmer can swim at a speed of 4 km/h. What should be the direction of the swimmer with respect to the river flow to cross the river perpendicular to river flow ?

A particle is thrown vertically upward. Its velocity at half of the maximum height is 10m/s. The maximum height attained by it is (g=10 ms^–2) :–

If number of divisions on circular scale is 50 in a screw gauge and pitch of screw is 1 mm then find least count of screw gauge.

Assertion (A) Two similarly charged bodies may attract each other.

Reason (R) When charge on one body (Q) is much greater than that on another (q) and they are close enough to each other, then force of attraction between Q and induced charges exceeds the force of repulsion between Q and q.

Assertion (A) Photodiode always works under reverse bias condition.

(Reason R) It is easier to detect current changes in reverse bias.

In the given circuit, current through the zener diode is :-

The figure shows a logic circuit with two inputs A and B and an output C. The voltage wave forms of A, B and C are as given, then logic circuit will be equivalent to :-

In the Bohr model of H-atom, if v is velocity of electron and r is its orbital radius, then in case of a hydrogen atom is :-

Pick out the unmatched pair from the following :-

The kinetic energy of an electron is 5 eV. Calculate the de-Broglie wavelength associated with it (h = 6.6 × 10^–34 Js, m_e = 9.1 × 10^–31 kg) :-

A photoelectric effect supports quantum nature of light because :

A. There is a minimum frequency of light below which no photoelectrons are emitted.

B. The maximum kinetic energy of photo electrons depends only on the frequency of light and not on its intensity

C. Above thresold frequency even when the  metal surface is faintly illuminated, the photoelectrons leave the surface immediately

D. Electric charge of photoelectrons is quantized

In the above true statement is :-

Young's double slit experiment the amplitude of two sources are 3a and a respectively. The ratio of intensities of bright and dark fringe will be :-

Figure shows a mixture of blue, green and red coloured rays incident normally on a right angled prism. The critical angles of the material of the prism for red, green and blue are 46º, 44º and 43º respectively. The arrangement will separate