An object placed 20cm in front of a mirror

Asked by admin @ 17/08/2021 in Physics viewed by 304 People

An object placed 20cm in front of a mirror is found to have an image 15cm (a) in front of it, (b) behind the mirror . Find the focal length of the mirror and the kind of mirror in each case.

Answered by admin @ 17/08/2021

CASE A

with sign convention

u= -20
v= -15

using mirror formula

1/v+1/u=1/f

-1/15-1/20 =1/f

-4-3/60=1/f

f= -60/7

since f is negative, therefore it is a concave mirror.

CASE B

U= -20
v= +15

using mirror formula

1/v+1/u= 1/ f

1/15-1/20=1/f

4-3/60=1/f

f=60

f is positive so it is a convex mirror

An object placed in front of a convex mirror

Asked by admin @ 23/08/2021 in Physics viewed by 338 persons

An object is placed in front of a convex mirror at a distance of 50cm. A plane mirror is introduced covering its lower half of the convex mirror. If the …

When an object is placed 20cm from a concave mirror

Asked by admin @ 03/08/2021 in Math viewed by 313 persons

When an object is placed 20cm from a concave mirror a real image magnified three times is formed find : A)the focal length of the mirrorB)where must be the …

Object placed between pole and focus of concave mirror

Asked by admin @ 20/08/2021 in Physics viewed by 271 persons

An object placed between the pole and focus of a concave mirror produces a virtual and enlarged image. Explain using mirror formula.

An object is placed 15 cm from a concave mirror

Asked by admin @ 03/08/2021 in Physics viewed by 340 persons

An object is placed 15 cm from a converging ( concave ) mirror that has a focal length of 10 cm a. determine the image located b. determine the magnification …

A convex mirror is placed to the right of an object. the image formed by the mirror will be a

Asked by maham237 @ 25/12/2020 in Physics viewed by 381 persons

real image that appears to be on the right of the mirror. real image that appears to be on the left of the mirror. virtual image that appears to be …

An object is placed at a distance of 20cm

Asked by admin @ 10/08/2021 in Physics viewed by 327 persons

an object is placed at a distance of 20 cm from a convex mirror of focal length 15 cm. find the position and nature of the image

An object 2cm high is placed at a distance

Asked by admin @ 23/08/2021 in Physics viewed by 336 persons

an object 2cm high is placed at a distance of 16cm from a concave mirror which produces a real image 3cm high. what is focal length of the mirror and …

A point object is placed on the principal axis

Asked by admin @ 20/08/2021 in Physics viewed by 377 persons

A point object is placed on the principal axis of a convex lens (f = 15 cm) at a distance of 30 cm from it. A glass plate (μ = …

A small plane mirror is placed at the centre

Asked by admin @ 20/08/2021 in Science viewed by 307 persons

27. A small plane mirror placed at the centre of a spherical screen of radius R. A beam of light is falling on the mirror,If the mirror makes n …

A plane mirror is placed horizontally on level ground

Asked by admin @ 20/08/2021 in Physics viewed by 303 persons

When a plane mirror is placed horizontally on a level ground at a distance of 60m from the foot of a tower, the top of the tower and its image …

An object is placed at a distance of 30cm

Asked by admin @ 20/08/2021 in Science viewed by 309 persons

An object is placed at a distance of 30cm from a concave lens of focal length 15cm. List four characteristic (nature, position,etc)of the image formed by the lens

Find the position of an object which when placed

Asked by admin @ 17/08/2021 in Science viewed by 319 persons

find the position of an object when placed in front of a concave mirror of focal length 20 cm produces a virtual image,which is twice size of object.

An object is placed at a distance of 30

Asked by admin @ 17/08/2021 in Science viewed by 400 persons

An object is placed at a distance of 30cm from a concave lens of focal length 15cm. List four characteristic (nature, position,etc)of the image formed by the lens