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The current in a coil of resistance 90 ohms is to be reduced by 90 percent. What value of resistance should be connected in parallel with it?

The resistance is connected in parallel. Hence, voltage across the required resistance S and 90Ω is the same, i.e. 0.9... View Article

When the interference occurs with non-coherent sources, _ of the superimposing waves add like _.

When the interference occurs with non-coherent sources, intensities of the superimposing waves add like scalars, I = I1 + I2

For sustained interference we need two sources which emit waves:

For sustained interference we need two sources which emit waves of constant phase difference.

In the given picture the Ring A at the bottom is positively charged. Another Ring B is brought and placed over it. Ring B hovers at a certain height above A. What could be the charge on Ring B.

There is a repulsion between the two rings and we know that like charges repel each other. Since Ring B is... View Article

The potential difference across a cell of emf E and internal resistance r is

V = E – Ir

Coherent sources can be created by the division of:

Coherent sources can be created by the division of both amplitude and wave front.

The light waves from two independent monochromatic light sources are given by: y1 =2 sinωt and y2 =3 cos ωt,then the correct statement is:

Two independent light sources cannot be coherent because they cannot generate waves having a constant phase difference.

Two sources of light are said to be coherent when both give out light waves of same______

Answer: Two sources of light are said to be coherent when both give out light waves of the same wave... View Article

Davisson and Germer experiment proves the

Davisson and Germer experiment is an excellent agreement between the experimental and theoretical value of wavelength of an electron.

A dielectric develops a _____in an external electric field.

Due to charge separation, a net dipole moment is created.

If cells are joined in series, they have ________.

same current. Explanation Batteries can either be connected in series, parallel or a combination of both. In a series circuit,... View Article

Three identical cells, each of 4 V and internal resistance r, are connected in series to a 6 ohm resistor. If the current flowing in the circuit is 2 A. The internal resistance of each cell is

Total emf = 3 x 4 = 12 V Total resistance = 6 + 3r Current in the circuit =... View Article

Light from a bulb is falling on a wooden table but no photo electrons are emitted as

It is because the work function of wood is more than the energy of the incident photons of light. Hence,... View Article

If the internal resistance of a cell is 20 ohm and resistance of the circuit is also 20 ohm. Will the current remain same whether the given n identical cells are in series or in parallel?

Since for same current R = r.

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