A circular coil of 100 turns, radius 10 cm, carries a current of 1 A. What is the magnetic field at the centre of the coil? ($\\mu_0 = 4\\pi \\times 10^{-7}$ T m A$^{-1}$)

In Young\'s double-slit experiment using light of wavelength $\\lambda = 600$ nm, the fringe width is 2 mm. If the distance between the slits is doubled, the new fringe width will be:

A convex lens of focal length 20 cm is placed in contact with a concave lens of focal length 30 cm. What is the power of the combination?

A ray of light travelling in a denser medium strikes a rarer medium at an angle of incidence $i$. The reflected ray is completely polarised. The angle between the reflected and refracted rays is:

In a single-slit diffraction experiment, the width of the central maximum is found to be 4 mm. If the slit width is halved, the width of the central maximum becomes:

The work function of a metal surface is 2 eV. If light of wavelength 400 nm is incident on it, what is the maximum kinetic energy of the emitted photoelectrons? ($h = 6.63 \\times 10^{-34}$ J s, $c = 3 \\times 10^8$ m/s, $1$ eV $= 1.6 \\times 10^{-19}$ J)

The de Broglie wavelength associated with an electron accelerated through a potential difference of 100 V is approximately: ($m_e = 9.1 \\times 10^{-31}$ kg, $e = 1.6 \\times 10^{-19}$ C, $h = 6.63 \\times 10^{-34}$ J s)

In a p-n junction diode, the potential barrier is approximately 0.3 V for Ge and 0.7 V for Si. If a Si diode is forward biased with a voltage of 0.5 V applied, what is the current through the diode?

In a transistor, the current gain $\\beta = 99$. If the base current $I_B = 20$ $\\mu$A, the collector current $I_C$ is:

In an LED (Light Emitting Diode), the colour of emitted light depends on: