Answer:
140°
Explanation:
The law of reflection states that the angle of redlection equals to the angle of incidence.
When light rays hit surface at 20°, they also leave the surface at the same angle
Since the whole surface has 180° then subtracting these two angles from total angle gives the the angle between the incident and reflected rays.
180°-20°-20°=140°
The angle of incidence and reflection are equal hence 140/2=70°
The question needed the angle between the incident and reflected rays which is already calculated as 140°
300 000 000 m/s in km/s
1000 m = 1km
300 000 000 m/s = 3 * 10⁸ m/s = 3 * 10⁵ *10³ m/s
= 3 * 10⁵ *10³ m/s
= 3 * 10⁵ km/s
Speed = 3 * 10⁵ km/s
Answer:
a) <em>8.33 x 10^-6 Pa</em>
b) <em>8.23 x 10^-11 atm</em>
c) <em>1.67 x 10^-5 Pa</em>
d) <em>1.65 x 10^-10 atm</em>
<em></em>
Explanation:
Intensity of the light 
= 2500 W/m^2
speed of light 
<u> </u>= 3 x 10^8 m/s
a) we know that the pressure for for a totally absorbing surface is given as
= 
= 2500/(3 x 10^8) = <em>8.33 x 10^-6 Pa</em>
b) 1 atm = 101325 Pa
= (8.33 x 10^-6)/101325 = <em>8.23 x 10^-11 atm</em>
c) for a totally reflecting surface
= 
= twice the value for totally absorbing
= 2 x 8.33 x 10^-6 = <em>1.67 x 10^-5 Pa</em>
d) 1 atm = 101325 Pa
= 2 x 8.23 x 10^-11 = <em>1.65 x 10^-10 atm</em>
