The force between like charges is _________.

In a large building, there are 15 bulbs of 40 W, 5 bulbs of 100 W, 5 fans of 80 W and 1 heater of 1 kW are connected. The voltage of electric mains is 220 V. The maximum capacity of the main fuse of the building will be ______.

Three wires of equal lengths are bent in the form of loops. One of the loops is circle, another is a semi-circle and the third one is a square. They are placed in a uniform magnetic field and same electric current is passed through them. Which of the following loop configuration will experience greater torque?

Above the neutral temperature the thermo emf ____________________.

In a transformer, eddy current loss is minimized by using ____________.

The electric and magnetic fields of an electromagnetic wave are _____.

When light is incident on a soap film of thickness 5 x 10^–5 cm, the wavelength of light reflected maximum in the visible region is 5320 Å. Refractive index of the film will be, _____.

Two plane mirrors are at right angles to each other. A man stands between them and combs hair with his right hand. In how many of the images will he be seen using his right-hand __________.

Two radiations with photon energies 0.9 eV and 3.3 eV respectively are falling on a metallic surface successively. If the work function of the metal is 0.6 eV, then the ratio of maximum speeds of emitted electrons in the two cases will be _____.

Wavelength of X-rays is ______ the wavelength of visible light

In J.J. Thomson e/m experiment, electrons are accelerated through 2.6 kV enter the region of crossed electric field and magnetic field of strength 3.0 x 10⁴ Vm^-1 and 1.0 x 10^-3 T, respectively, and pass through it and undeflected, then the specific charge is _____.

A common - emitter amplifier has a voltage gain of 100, an input impendence of 100Ω and an output impedence of 200 Ω. The product of voltage gain and current gain is _________

The frequency range of 3 MHz to 30 MHz is used for ______.

The device which is a combination of a receiver and a transmitter is ___________________.

The gravitational waves were theoretically proposed by _____.

(i) Electric field lines donot have sudden breaks why is it so?
(ii) Explain why two field lines never cross each other at any point.

Give any one definition of power factor.

Which part of Electromagnetic is absorbed from sunlight by ozone layer?
(i) Write its source and
(ii) mention its uses.

Write the expression for angular resolution.

An electron and an alpha particle have same kinetic energy. How are the de Broglie wavelengths associated with them related?

What is the reason for using lighter nuclei as moderators?

Explain the need for a feedback circuit in a transistor oscillator.

What do you mean by noise in communication?

How does the manipulation of colours obtain in nanoscale structure?

Explain the Lightning arrester or lightning conductor.

Explain the determination of unknown resistance using meter bridge.

Discuss the conversion of galvanometer into an ammeter and also a voltmeter.

What is the magnetic field at point O due to current carrying wires shown in the figure?

Show that Lenz’s law is in accordance with the law of conservation of energy.

The charge on a parallel plate capacitor varies as q = q_o cos 2\(\pi \gamma \)t. The plates are very large and close together. (area - A. separation - d) find the displacement current through the capacitor?

What is the focal length of the combination if the lenses of focal lengths –70 cm and 150 cm are in contact? What is the power of the combination?

The graph shows the variation of stopping potential with frequency of incident radiation for two photosensitive metals A and B. Which one of the two has higher value of workfunction? Justify your answer.

What are radioactive elements? What are the factors that affect radio activity?