Physics
Assertion (A) : Concave mirror is used as doctor's head mirror.
Reason (R) : If a parallel beam of light is incident on a concave mirror, the mirror focuses the beam to a point.
- both A and R are true and R is the correct explanation of A
- both A and R are true and R is not the correct explanation of A
- assertion is false but reason is true
- assertion is true but reason is false
Answer
both A and R are true and R is the correct explanation of A
Explanation
Assertion (A) is true: A concave mirror is used as a doctor's head mirror because it can direct and concentrate light into the patient’s body parts (such as teeth, nose, throat, ear, etc.) for better visibility.
Reason is true: When a parallel beam of light (like light from a lamp) falls on a concave mirror, the mirror reflects and converges the rays to its focal point, producing a bright, concentrated spot of light.
This property of focusing parallel rays to a point is precisely why concave mirrors are used in head mirrors, as it enables the doctor to project an intense beam exactly where it is needed. Therefore, the reason correctly explains the assertion.
Related Questions
Assertion (A) : For a real image formed by a spherical mirror, linear magnification (m) is positive.
Reason (R) : Both u and v are negative for a real image.
- both A and R are true and R is the correct explanation of A
- both A and R are true and R is not the correct explanation of A
- assertion is false but reason is true
- assertion is true but reason is false
Assertion (A) : For an object placed symmetrically when the angle θ between the mirrors is 72°, the number of images formed is 4.
Reason (R) : If n = 360°/θ is odd, the number of images for an object placed symmetrically is equal to n.
- both A and R are true and R is the correct explanation of A
- both A and R are true and R is not the correct explanation of A
- assertion is false but reason is true
- assertion is true but reason is false
Assertion (A) : A student is given a spherical mirror of focal length -10 cm. He identifies it as a concave mirror.
Reason (R) : Focal length of a concave mirror is always positive.
- both A and R are true and R is the correct explanation of A
- both A and R are true and R is not the correct explanation of A
- assertion is false but reason is true
- assertion is true but reason is false
What is a spherical mirror?