Class 12th

In the above diagram, balance length for E' is ℓ₀. If cross sectional area of wire AB is doubled then what will be new balancing length ?

Two pipes are each 50 cm in length. One of them is closed at one end while the other is open at both ends. The speed of sound in air is 340 m s^–1. The frequency at which both the pipes can resonate is :-

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 :-