Question

A convex mirror has a focal length of 40 cm .determine the object position for which the resulting image will be erect and four times the size of the object.


pls reply soon I have physics test tomorrow

Answer 1

f=40cm..,v=-4u
we know,
1÷u + 1÷v = 1÷f

Answer 2

Answer:

The object is 30 cm away in front of mirror.

Explanation:

thanks for A2A. It is given that image is 4 times the object.Thus,

(-V/u) =4

U(-V) /4

Now using the mirror formula also here

f=(-40) (focal length of concave mirror is negative)

1/f=1/v +1/u

1/(-40)=1/V + (-4)/V

1/(-40)= (-3)/V

V=3*40

=120

u= (-120/4)

=(-30)

u= (-30)cm

Thus the object is 30 cm away in front of mirror