Answer:
Energy consumed by the electric kettle in 9.5 min =Pt=(2.5×10
3
)×(9.5×60)=14.25×10
5
J
Energy usefully consumed =msΔT=3×(4.2×10
3
)×(100−15)=10.71×10
5
where s=4.2J/g
o
C= specific heat of water and boiling point temp=100
o
C
Heat lost =14.25×10
5
−10.71×10
5
=3.54×10
5
<h3><u>Answer;</u></h3>
Large mirrors are easier to build than large lenses.
<h3><u>Explanation;</u></h3>
- <em><u>Reflector telescopes have a number of advantages as compared to refracting telescopes and other types of telescopes. </u></em>
- <em><u>Reflector telescopes do not suffer from chromatic aberration because all wavelengths will reflect off the mirror in the same way. The support for the objective mirror is all along the back side so they can be made very large.</u></em>
- Additionally, reflector telescopes are cheaper to make than refractors of the same size. Also since in reflector telescopes light is reflecting off the objective, rather than passing through it, only one side of the reflector telescope's objective needs to be perfect.
if it moves 7m/s, that means every second it goes 7m. Now we just multiply by the time (20 seconds) and end up with 140m.
Complete question:
A light bulb emits light that travels uniformly in all directions. Detailed measurements show that at a distance of 56 m from the bulb, the amplitude of the electric field is 3.78 V/m. What is the average intensity of the light?
Answer:
The average intensity of the light is 0.02 W/m²
Explanation:
Given;
Amplitude of the electric field, E₀ = 3.78 V/m
The average intensity of the light is calculated as follows;
where;
is the average intensity of the light
c is speed of light = 3 x 10⁸ m/s
Therefore, the average intensity of the light is 0.02 W/m²
