Question 101:
easyAssertion (A): Keeping a point object fixed, if a plane mirror is moved, the image will also move.
Reason (R): In case of a plane mirror, distance of object and its image is equal from any point on the mirror.
Assertion (A) is true; the image position is relative to the mirror, so it moves with the mirror. Reason (R) is true as per the property of plane mirrors, where \(OP = IP\). (R) correctly explains (A) as image movement maintains this property.
Question 102:
easyAssertion (A): If there is relative motion between a point object & a plane mirror then there must be relative motion between object and image formed by mirror.
Reason (R): If the gap between object and mirror will change, the gap between object and image remains same.
Assertion A is true because if the object moves relative to the mirror, its image also moves, causing relative motion between object and image. Reason R is false because for a plane mirror, the object-image gap is twice the object-mirror gap, so if the object-mirror gap changes, the object-image gap also changes.
Question 103:
easyAssertion (A): When the upper half of a converging lens is missing, a real image formed by the lens for a real object will lack its lower half.
Reason (R): The real image formed by a thin lens for a real object will be always erected.
Assertion A is false because even with half the lens missing, a complete image is formed, but its intensity is reduced. Reason R is false as real images formed by a thin lens for a real object are generally inverted, not always erected.
Question 104:
easyAssertion (A): A parallel beam of light travelling in air can be displaced laterally by a parallel transparent slab by distance more than the thickness of the plate.
Reason (R): The lateral displacement of light travelling in air increases with fall in value of refractive index of slab.
Assertion A is false as the lateral displacement of light through a parallel slab is always less than or equal to its thickness. Reason R is false because lateral displacement decreases as the refractive index of the slab falls.
Question 105:
easyAssertion (A): A virtual image formed by plane mirror may be inverted.
Reason (R): Longitudinal magnification in this case of plane mirror is \(-1\).
Assertion A is true because a plane mirror forms a laterally inverted image. Reason R is true because for a plane mirror, longitudinal magnification \(m_L = - (v/u)^2 = -1\). However, longitudinal magnification does not explain lateral inversion.
Question 106:
easyAssertion (A): A convex lens of glass \((\mu = 1.5)\) behaves as a diverging lens when immersed in a medium of refractive index \(\mu = 1.65\).
Reason (R): A diverging lens is thinner in the middle and thicker at the edges.
Assertion A is true; if \(mu_{medium} > \mu_{lens}\), a convex lens becomes diverging due to sign change in the lens maker's formula. Reason R is true as it describes a typical concave (diverging) lens shape. But the shape of a diverging lens does not explain the behavioral change of a convex lens.
Question 107:
easyAssertion (A): Biconvex lens can form virtual image of a virtual object.
Reason (R): Nature of lens depends on refractive index of surrounding.
A biconvex lens can form a virtual image of a virtual object. The nature of a lens (converging/diverging) depends on the refractive index of the lens material relative to the surrounding medium. Therefore, both A and R are true, and R is the correct explanation of A.
Question 108:
easyAssertion (A): The minimum length of mirror required to form complete image of man of height \(H) is \(H/2\).
Reason (R): Image of an object is obtained if incident light ray reaches the reflecting surface.
The minimum length of a plane mirror to see a full image of a person of height \(H) is \(H/2\). Image formation occurs when light rays reach and reflect from a surface. Both statements are true, but R is a general principle and does not explain the specific \(H/2\) relation.
Question 109:
easyAssertion (A): Concave mirror can not form real image of real object.
Reason (R): Concave mirror behave as a diverging mirror.
A concave mirror is a converging mirror and can form real images of real objects when the object is beyond the focal point. Therefore, both Assertion (A) and Reason (R) are false.
Question 110:
easyAssertion (A): Radius of curvature of a concave mirror is \(20 \text{cm}\). If a real object is placed in front of a mirror at \(10 text{cm}\) from pole of the mirror, image is formed at infinity.
Reason (R): When object is placed at focus of a converging optical system then its image is formed at infinity.
For a concave mirror, \(R = 20 \text{cm}\), so \(f = R/2 = 10 \text{cm}\). An object placed at the focal point of a converging mirror forms its image at infinity. Both A and R are true, and R correctly explains A.