ECAT Physics MCQs

The law of reflection gives equal incidence and reflection angles.
Both are measured from the normal.

Coulomb's law describes electrostatic force between point charges.
The force acts along the line joining the charges.

A plane mirror forms the image the same distance behind as the object is in front.
Therefore the object distance is 2 m.

Electric field is a vector quantity E=F/q.
Its direction is the force direction on a positive test charge.

Refractive index is n=c/v.
N=3.0×10^8 / 2.0×10^8 = 1.5.

Electric potential is a scalar measured in volts.
Potential difference drives charge movement in circuits.

Use v=c/n.
V=3.0×10^8/1.25 = 2.4×10^8 m/s.

Current is I=Q/t.
Its SI unit is the ampere.

Snell's law gives 1×sin30° = 1.5 sinr.
Sinr=0.5/1.5≈0.333.

Potential difference is V=W/Q.
One volt equals one joule per coulomb.

The critical angle satisfies sin c = 1/1.5.
C≈sin^-1(0.667)=41.8°.

Resistance relates voltage and current through Ohm's law.
Its SI unit is the ohm.