(See also at set 1)

Answer:

Answer: (Hint: steps are same as in the above question, except it is concave mirror, m = -1/2. Compute f in first case i.e. f = -20 cm and the compute u in case II i.e. u = 80 cm)

Answer:

Answer: The reflected ray will be rotated twice w.r.t to the angle of rotation of mirror. i.e. $2\theta$

Consider the following figure:

As shown, mirror M is rotated by an angle $\phi$. Let I be incident ray, N be normal and R is reflected ray.

Before rotation, let the incident angle be $\theta$

After rotation, normal moves by angle $\phi$,

Answer:

**Q1: When an object is placed at a distance of 60 cm from a convex mirror, the magnification produced is 1/2.****Where should the object be placed to get a magnification of 1/3?**Answer:

**Q2: When an object is kept at a distance of 60cm from a concave mirror, the magnification is 1/2. Where should the object be placed to get magnification of 1/3?**

Answer: (Hint: steps are same as in the above question, except it is concave mirror, m = -1/2. Compute f in first case i.e. f = -20 cm and the compute u in case II i.e. u = 80 cm)

**Q3(CBSE Board): A concave lens made of material of refractive index (n**

_{1}) is kept in a medium of refractive index (n_{2}). A parallel beam of light is incident on the lens. Complete the path of the rays of light emerging from a concave lens if:**(a) n**

_{1}> n_{2}**(b) n**

_{1}= n_{2}**(c) n**

_{1}< n_{2}**Q4: A convex lens made of material of refractive index (n1) is kept in a medium of refractive index (n2). A parallel beam of light is incident on the lens. Complete the path of the rays of light emerging from a concave lens if:**

**(a) n1 > n2**

**(b) n1 = n2**

**(c) n1 < n2**

Answer:

**Q5: Which of the two has a great power? A lens of short focal length or a lens of large focal length?**

Answer: lens of short focal length.

**Q6: When a convex lens and a concave lens of equal focal lengths are placed side by side, what will be the equivalent power and the combined focal length.**

**Answer**: Equivalent Power = 0 and Combined focal length = infinity.

**Q7: When a plane mirror is rotated by an angle $\theta$, what will be the angle of rotation of the reflected ray for the fixed incident ray?**

Answer: The reflected ray will be rotated twice w.r.t to the angle of rotation of mirror. i.e. $2\theta$

Consider the following figure:

As shown, mirror M is rotated by an angle $\phi$. Let I be incident ray, N be normal and R is reflected ray.

Before rotation, let the incident angle be $\theta$

After rotation, normal moves by angle $\phi$,

**Q8: With respect to air the refractive index of kerosene is 1.44 and that of diamond is 2.42. Calculate the refractive index of diamond with respect to kerosene.**

Answer: