Question

an optician holds a test card 50cm away behind the patient then looks in a plane mirror which is 100cm.How far is the test card from the patient's eyes?​

Answer 1

Answer:

250 cm

Explanation:

At first it is 100 cm away then reflection come back for 150 cm so it is added to get 250cm

100+100+50=250

Answer 2

Given:

Distance of patient from mirror = 100 cm

Distance of test card from patient = 50 cm

To find:

Test card from patients eyes or distance of image of test card =?

(The question should state that how far is the image of the test card from the patient's eyes)

Solution:

Step 1:

• Distance of test card from mirror= Distance of patient from mirror + Distance of test card from a patient
• Distance of test card from mirror= 100 cm + 50 cm
• Distance of test card from mirror= 150 cm

Step 2:

• Because it is a plane mirror image of test card if formed at equal distance in the plane mirror as object.
• Therefore, the image of the test card = 150 cm

• Now to find the distance of the image from the patient's eyes calculate add the distance between the patient and mirror and the distance of the image in the plane mirror.

Step 3:

• Image of test card from patient's eyes = Distance of patient from mirror + Distance of image of test card in the mirror
• Image of test card from patient's eyes = 100 cm + 150 cm
• Image of test card from patient's eyes = 250 cm

Hence, the image of the test card is 250 cm from the patient's eyes.