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

Explanation

• According to Gauss's law, the net electric flux through a closed surface depends on the total charge enclosed within it.
• An electric dipole consists of equal and opposite charges, +q and -q. The net enclosed charge is zero.
• The formula is Flux = Q_enclosed / ε0 = 0 / ε0 = 0.

Last verified on 28-10-2026

Explanation

• An angle is dimensionless because it is defined as the ratio of arc length to radius, and both have the dimension of length.
• The SI unit of angle is the radian (rad).
• Other dimensionless quantities include strain, refractive index, and coefficient of friction.

Last verified on 28-10-2026

Explanation

• A moving coil galvanometer works on the principle that a current-carrying coil experiences torque when placed in a magnetic field.
• The torque causes the coil to rotate, and the attached pointer moves over a calibrated scale to indicate the electric current.
• A stronger current produces greater torque and a larger deflection, within the instrument’s normal operating range.

Last verified on 28-10-2026

Explanation

Torque on a current carrying coil in uniform magnetic field

tau = N I A B sinθ

where θ is the angle between the normal to the plane of coil and the magnetic field B.

When plane of coil is parallel to B, normal is perpendicular to B, θ = 90°, sinθ = 1, torque is maximum.

When plane of coil is perpendicular to B, normal is parallel to B, θ = 0°, sinθ = 0, torque is minimum (zero).

So torque is minimum when plane of coil is placed Perpendicular to the magnetic field.

Last verified on 28-10-2026

Explanation

• The capacitance of a parallel-plate capacitor is directly proportional to the plate area and inversely proportional to the distance between the plates.
• Doubling the plate area doubles the capacitance, while halving the distance doubles it again.
• Therefore, the new capacitance becomes 2 x 2 = 4 times the original capacitance.
• The formula is C = εA / d, where A is plate area, d is the separation, and ε is the permittivity of the material between the plates.

Last verified on 28-10-2026

Explanation

• The electric field lines of a positive point charge point outward, away from the charge.
• As we move farther away from the charge, the electric field strength decreases according to the inverse-square law.
• The electric field strength is given by E = kQ / r^2, where Q is the charge and r is the distance from it.

Last verified on 28-10-2026