Question

what is rhe angle of incidence of a ray if the angle between the incident and reflected ray is 120 degree​

Answer 1

Given:

• the angle between the incident and reflected ray is 120 degree.

To Find:

• the angle of incidence

Solution:

❍ As given in the diagram attached you can see that the

• Angle of incidence
• Angle of reflection
• And the normal

All lie in the same plane.

It is said that the angle between the incident ray and the relacted ray is 120°

Which means,

• ➪ $\blue\angle { \blue{\bf{ \: incidence + refelction = 120 \degree}}}$

$\purple{ \mathfrak{ \underline{ \dag \: As \: we \: know \: that}}}$

${\blue{ \bigstar{ \underline{ \boxed{ \pink{ \mathfrak{ angle \: of \: incidence \: = \: angle \: of \:reflection}}}}}}}$

So, let's consider angle of reflection as angle of incidence

Now, their sum is 120 degrees,

$\mapsto\sf \: { \red{\angle \: i \: + \angle \: i = 120 \degree}} \\ \\ \\ \mapsto\sf \: { \red{2\angle \: i = 120 \degree}} \: \: \: \: \: \: \: \: \: \: \\ \\ \\ \mapsto\sf \: { \red{\angle \: i \: = \cancel\frac{120}{2} }} \: \: \: \: \: \: \: \: \: \: \: \: \\ \\ \\ \mapsto\sf \: { \red{\angle \: i \: = 60 \degree}} \: \: \: \: \: \: \: \: \: \: \: \:$

hence,

• The angle of reflection is 60°

Knowledge cell :

Light

• Light is the source of energy which gives us the sensation of vision

Reflection of Light

• The bouncing back of light from the surface of an object is called reflection of the light

Normal

• the line perpendicular to the surface of the mirror

Characteristics of light

• Light travels in a straight line path
• Light is an invisible from of energy

Speed of Light

• Air/ vaccume = 3×10⁸m/s
• Glass = 2×10⁸ m/s

Fun Fact

• Light doesn't require a medium to propagete.

happy learning