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

Explanation

• Surface tension causes a liquid drop to minimize its surface area, making it tend toward a spherical shape.
• Surface tension arises due to the cohesive forces between liquid molecules at the surface.

Last verified on 28-10-2026

Explanation

• An ammeter measures the electric current flowing through a circuit.
• It is connected in series so that the same current flowing through the circuit also passes through the ammeter.
• An ammeter has very low resistance to minimize its effect on the current being measured.

Additional information:

• A voltmeter, in contrast, is connected in parallel to measure the potential difference across a component.

Last verified on 28-10-2026

Explanation

• Impulse J=F⋅Δt represents the change in momentum of an object.
• It is directly proportional to the force applied and the time duration of application.
• Impulse measures the effect of force over a time interval.

Last verified on 28-10-2026

Explanation

Scalar product = AB cosθ

Magnitude of vector product = AB sinθ

For equal magnitudes:

AB cosθ = AB sinθ

cosθ = sinθ

tanθ = 1

θ = 45°

So magnitude is equal at 45°.

Last verified on 28-10-2026

Explanation

• According to Coulomb's law, the electrostatic force is directly proportional to the product of the two charges and inversely proportional to the square of the distance between them.
• Doubling both charges makes the force 4 times greater, while doubling the distance makes the force 1/4 as large.
• The combined effect is 4 x 1/4 = 1. Therefore, the force remains the same.
• Coulomb's law applies to stationary point charges in a vacuum or approximately in air.

Last verified on 28-10-2026

Explanation

• An elastic collision is a collision in which both total kinetic energy and total momentum are conserved.
• Momentum is conserved in both elastic and inelastic collisions, provided the system is isolated.

Last verified on 28-10-2026

Explanation

• According to Newton's second law, acceleration equals net force divided by mass.
• If the mass doubles and the force becomes half, the new acceleration is one-fourth of the original acceleration.
• For example, if the original acceleration is 2 m/s^2, the new acceleration will be 0.5 m/s^2.

Last verified on 28-10-2026

Explanation

• The scalar product (dot product) of two vectors is given by A · B = AB cosθ.
• The scalar product is maximum when the angle between the vectors is 0°, because cos0° = 1.
• At 0°, both vectors point in the same direction, so their dot product equals AB.
• At 90°, the dot product is zero because cos90° = 0.

Last verified on 28-10-2026

Explanation

• Least count is the smallest measurement that an instrument can read or measure.
• A smaller least count generally means greater precision.
• Because the instrument can detect smaller changes in a measurement.

Last verified on 28-10-2026