Explanation

• The negative of the potential gradient is equal to the electric field intensity.
• The electric field points in the direction in which electric potential decreases most rapidly.
• The mathematical relation is E = -dV/dr, where E is electric field intensity and V is electric potential.
• The negative sign indicates that electric potential decreases in the direction of the electric field.

Last verified on 28-10-2026

Explanation

• In a transformer, the frequency of AC remains the same in both the primary and secondary coils.
• The voltage can increase or decrease depending on the turns ratio of the coils.

Last verified on 28-10-2026

Explanation

• The relation between time period (T) and orbital radius (r) is: T² ∝ r³
• This is given by Kepler's Third Law - The Law of Periods.

Last verified on 28-10-2026

Explanation

• Pascal's law states that a change in pressure applied to an enclosed fluid is transmitted equally and undiminished throughout the fluid and to the walls of its container.
• The pressure is transmitted in all directions, not just in the direction of the applied force.
• This principle is used in hydraulic brakes, hydraulic lifts, and hydraulic presses.
• Pressure is calculated as P = F / A, where F is force and A is the area over which the force acts.

Last verified on 28-10-2026

Explanation

• A voltmeter measures potential difference (voltage) between two points in a circuit.
• To do this correctly, it must be connected in parallel with the component across which the voltage is to be measured.

Last verified on 28-10-2026

Explanation

Energy stored in a capacitor:

U = 1/2 C V^2

U is directly proportional to V^2.

If V' = 2V

U' = 1/2 C (2V)^2 = 4 x 1/2 C V^2 = 4U

Answer: Four times the initial value.

Last verified on 28-10-2026

Explanation

At maximum height final velocity v = 0

Using 3rd equation of motion:

v^2 = u^2 - 2gh

0 = (10)^2 - 2 x g x h

h = 100 / 2g

If g = 10 m/s^2

h = 100 / 20 = 5 m

Last verified on 28-10-2026

Explanation

Escape velocity formula:

v_e = sqrt(2GM / R) = sqrt(2gR)

Where:

G = gravitational constant

M = mass of planet

R = radius of planet

It depends on mass and radius of the planet.

It is independent of mass of the object (the body which is escaping).

Last verified on 28-10-2026

Explanation

When a wire is stretched, its volume remains constant:

V = A x L = constant

So if length becomes 3 times:

L' = 3L

A' = A / 3

Resistance formula: R = rho L / A

New resistance:

R' = rho L' / A' = rho (3L) / (A/3) = 9 rho L / A = 9R

Last verified on 28-10-2026

Explanation

• Silicon is a semiconductor that generally has a negative temperature coefficient of resistance.
• As the temperature of silicon increases, more charge carriers become available, so its electrical resistance usually decreases.
• Most pure metals, such as iron and mercury under ordinary conditions, have a positive temperature coefficient of resistance.
• It means their resistance generally increases with temperature.

Last verified on 28-10-2026