List of top Physics Questions on Electric Field Intensity

A parallel plate capacitor of capacitance \(1\ \mu\text{F}\) is charged to a potential difference of \(20\ \text{V}\). The distance between plates is \(1\ \mu\text{m}\). The energy density between plates of capacitor is:

A steady current \(I\) flows through a long straight wire of radius \(a\). The current is uniformly distributed across its cross-section. The ratio of the magnetic fields due to the wire at distances \(\frac{a}{4}\) and \(3a\) respectively from the axis of the wire is:

Two electrons are moving with different kinetic energies. If the first electron is moving with kinetic energy \(k\) and the second electron with kinetic energy \(4k\), the ratio of their de Broglie wavelengths respectively will be:

What is the relative decrease in focal length of a lens for an increase in optical power by \(0.1\ \text{D}\) from \(2.5\ \text{D}\)?

An infinitely long line charge distribution produces a field of $9 \times 10^4\ \text{NC}^{-1}$ at a distance of $2\text{ cm}$. The linear charge density of the distribution is:

A body of $20\text{ g}$ and $+50\ \mu\text{C}$ charge is suspended from the ceiling by a string. If a horizontal electric field of $10\text{ kV/m}$ is applied, the angle between the string and vertical direction is: (Take $g = 10\text{ N/kg}$)

A copper ball of density $8.0\text{ g/cc}$ and $1\text{ cm}$ in diameter is immersed in oil of density $0.8\text{ g/cc}$. The charge on the ball if it remains just suspended in oil in an electric field of intensity $600\pi\text{ V/m}$ acting in the upward direction is __________. Fill in the blank with the correct answer from the options given below. (Take $g = 10\text{ m/s}^2$)

A negatively charged object A is repelled by another charged object B. However, an object C is attracted to object B. Which of the following is the most probable for the charge of object C?