physics light qns

SgStudentStressed SG

a horizontal ray of light incident on a plane mirror M. The mirror is inclined at 40 degrees to to horizontal ground. the mirror is now turned 30 degrees to the left. determine the angle the reflected ray would turn through.

so what i dont understand here is the meaning of determine the angle the reflefted ray would turn through. by my understanding it means to find the angle change from the first reflected to the final reflection. however my teacher says it is the difference of the two angle of reflections. which one would it be n how should i explain it to her? thanks

syncopation_music SG

I need to establish a few point before we can answer your question

Are you referring to refraction ? if yes , what is the refractive index ?

You question is very vague as i can see you mixed up between the Principle of Reflection of Light and Refraction itself .Able to copy the whole question for us to assess .

thanks

syncopation_music SG

"turned 30 degrees to the left" can have different meaning .Is it reached 30 degree (which is 150 degree on the left) or turn from the original position to a further 30 degree.

Different meaning mean different value .thanks

eagle SG

Hi, I agree with syncopation on your question being unclear. Please post the full question if you have it.

To the best of what I can make out, and disecting the question you have posted,

a horizontal ray of light incident on a plane mirror M. The mirror is inclined at 40 degrees to to horizontal ground.

My guess is 90 degrees to the mirror. Means zero angle of incidence. Reflected ray will go back via the same path as incident ray.

the mirror is now turned 30 degrees to the left. determine the angle the reflected ray would turn through.

The angle of incidence is now 30 degrees, no matter you turn clockwise or anti-clockwise. The angle of reflection will also be 30 degrees.

Hence, the reflected ray would have turned through 60 degrees.

SgStudentStressed SG

yep ur rite eagle i gt that ans too

frekiwang SG

60 degree, very standard MCQ question in O. Angle turned through by the reflected ray = 2 times of the angle turned by the mirror, given the incident ray remains unchanged.