A ray of light is incident on 'a plane mirror ...-Physics

2 months ago

Please I still don't understand

1 year ago

Let's go through this step by step carefully.

Given:
Angle of incidence = 20°
Mirror is rotated by twice this angle, meaning:
2
×
20
°
=
40
°
2×20°=40°
Key Concept:
When a plane mirror is rotated by an angle
𝜃
θ, the reflected ray rotates by
2
𝜃
2θ.

Here, since the mirror is rotated by 40°, the reflected ray rotates by:
2
×
40
°
=
80
°
2×40°=80°
Finding the Total Angle:
The original angle between the incident ray and the reflected ray (before rotating the mirror) is:

Angle of incidence
+
Angle of reflection
=
20
°
+
20
°
=
40
°
Angle of incidence+Angle of reflection=20°+20°=40°
After rotation, the new total angle between the incident ray and the reflected ray is:

40
°
+
80
°
=
120
°
40°+80°=120°
Correct Answer:
D. 120°

Emmanueloluwaseun

2 years ago

∖ Ⅰ ∕ ∕
∖ Ⅰ ∕ ∕
∖ Ⅰ ∕ ∕
∖ Ⅰ ∕ 80⁰ ∕
∖20 ⁰ Ⅰ 20 ⁰ ∕ (2X40) ∕
−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−

20+20+80 = 120⁰

hakmuz

1 year ago

Let's go through this step by step carefully.

Given:
Angle of incidence = 20°
Mirror is rotated by twice this angle, meaning:
2
×
20
°
=
40
°
2×20°=40°
Key Concept:
When a plane mirror is rotated by an angle
𝜃
θ, the reflected ray rotates by
2
𝜃
2θ.

Here, since the mirror is rotated by 40°, the reflected ray rotates by:
2
×
40
°
=
80
°
2×40°=80°
Finding the Total Angle:
The original angle between the incident ray and the reflected ray (before rotating the mirror) is:

Angle of incidence
+
Angle of reflection
=
20
°
+
20
°
=
40
°
Angle of incidence+Angle of reflection=20°+20°=40°
After rotation, the new total angle between the incident ray and the reflected ray is:

40
°
+
80
°
=
120
°
40°+80°=120°
Correct Answer:
✅ D. 120°