A clock hung on a wall has marks instead of numerals on its dial. On the adjoining wall, there is a plane mirror and the image of the clock in the mirror indicates the time 7:10 . Then the time on the clock is

Question

A clock hung on a wall has marks instead of numerals on its dial. On the adjoining wall, there is a plane mirror and the image of the clock in the mirror indicates the time 7:10 . Then the time on the clock is (A)  7:10  (B)  4:50  (C)  5:40  (D)  10:7

Tardigrade Admin · Accepted Answer

In a plane mirror the image undergoes depth inversion hence, the time on the image is as much ahead of

12 h 0

min as the time on actual clock is behind

12 h 0

min.
Time on the actual clock

= 7 h 10

min
Time on the image clock

= (12 h

and

0

min)

- (7 h

and

10

min)

= 4 h

and

50

min

Q. A clock hung on a wall has marks instead of numerals on its dial. On the adjoining wall, there is a plane mirror and the image of the clock in the mirror indicates the time $7 : 10$ . Then the time on the clock is

$7 : 10$

$4 : 50$

$5 : 40$

$10 : 7$

In a plane mirror the image undergoes depth inversion hence, the time on the image is as much ahead of $12 h 0$ min as the time on actual clock is behind $12 h 0$ min.
Time on the actual clock $= 7 h 10$ min
Time on the image clock
$= (12 h$ and $0$ min) $- (7 h$ and $10$ min) $= 4 h$ and $50$ min

Q. A clock hung on a wall has marks instead of numerals on its dial. On the adjoining wall, there is a plane mirror and the image of the clock in the mirror indicates the time 7:10 . Then the time on the clock is

7:10

4:50

5:40

10:7