CBSE physics
Sponsor Area
A point charge +Q is placed at point O as shown in the figure. Is the potential
difference VA – VB is positive, negative or zero?
Electric potential at a distance r from the point charge +Q is given by,
Potential at point A is, 
Similarly, potential at point B is given by, 
Since rA < rB 
Sponsor Area
How does the electric flux due to a point charge enclosed by a spherical Gaussian surface get affected when its radius is increased?
According to Gauss's law, flux through a closed surface is given by,
Here, q is the charge enclosed by the gaussian surface.
That is, on increasing the radius of the gaussian surface, charge q remains unchanged.
So, flux through the gaussian surface will not be affected when its radius is increased.
Write the underlying principle of a moving coil galvanometer.
When a current-carrying coil is placed in a magnetic field, it experiences torque. This is the underlying principle of a moving coil galvanometer.
Why are microwaves considered suitable for radar systems used in aircraft navigation?
Microwaves are considered suitable for radar systems used in aircraft navigation because they have a short wavelength range (10-3 m to 0.3 m), which makes them suitable for long range communication.
Define 'quality factor' of resonance in a series LCR circuit. What is its SI unit?
Quality factor relates the maximum or peak energy stored in the circuit (the reactance) to the energy dissipated (the resistance) during each cycle of oscillation.
Quality factor is expressed as, 
Q-factor is a dimensionless quantity.
Sponsor Area
Mock Test Series
Mock Test Series