Assertion(A): Light does not travel in the same direction while going from one medium to the other.

Reason (R): Speed of light does not change as it enters from one transparent medium to the other.

Assertion(A): Presbyopia is a defect of vision which usually happens in old age.

Reason (R): Due to ageing, the ciliary muscles gets weakened and flexibility of eye lens reduces.

Assertion(A): Fuse is the most important safety device, used for protecting the circuits.

Reason (R): Fuse wire stays strong and intact in the circuit if current increases excessively due to short-circuiting or overloading.

Assertion(A): Speed of light in diamond is \(\frac{1}{2.42}\) times the speed of light in air/vacuum.

Reason (R): Refractive index of diamond is 2.42.

Assertion(A): A convex mirror always forms an image behind it and the image formed is virtual.

Reason (R): According to the sign convention, the focal length of a convex mirror is positive.

Assertion(A): It is possible to change electric current in a circuit without changing the voltage.

Reason (R): A variable resistance is a component that can regulate current by changing the resistance of the circuit without changing the voltage source.

Assertion(A): Earth wire is an important safety device which ensure that any leakage of current to a metallic body does not give any severe shock to the user.

Reason (R): Earth wire provides a high resistance conducting path for the flow of current.

Assertion(A): Principal focus of a spherical mirror lies midway between the pole and centre of curvature.

Reason (R): The relation between Radius of curvature and focal length of a spherical mirror is R = 2f.

Assertion(A): All the appliances in domestic circuit are connected in parallel combination.

Reason (R): In parallel combination, electrical consumption is least.

Assertion(A): In an open circuit, electric current flows from one terminal to the other terminal of a battery.

Reason (R): Electric current always flows from higher potential to the lower potential.