1. It increases sensitivity by providing amplification to RF signal
2. It eliminates image frequency interference
3. It increases selectivity
4. It reduces noise level

Assertion (A): A backward wave oscillator can be used as a sweep generator.

Reason (R): The frequency of oscillation of a backward wave oscillator can be changed by varying the voltage which controls the beam velocity.

Assertion (A): The turn on time of SCR is about 1 to 4 ms.

Reason (R): The turn off time of SCR is about 10 to 300 ms.

Assertion (A): Derivative control action cannot be used alone.

Reason (R): Derivative control action is effective only during transient periods.

Assertion (A): In intrinsic semiconductors, the charge concentration increases with temperature.

Reason (R): At higher temperatures, the forbidden energy gap in semiconductors is lower.

Assertion (A): In a perfect capacitor, the current density is given by ω ∈₀E₀∈^'_rcos(ωt + 90°), where ∈_r^' is real part of dielectric constant.

Reason (R): In a perfect capacitor, dielectric losses are zero.