Answer:
80%
Explanation:
The thermal energy output by the oven is 800 J which is the useful energy that can be utilized for cooking.
The electrical energy input to the oven is 1000 J.
The efficiency of the oven =
(Useful energy output)/(Total energy input to the oven) x 100
Hence, the efficiency of the oven is 80%.
Answer:
(a) λ = 4136 nm → infrared
(b) λ = 413.6 nm → visible light
(c) λ = 41.36 nm → ultraviolet
Explanation:
The wavelength of infrared is on the range of 700 nm to 1000000 nm
The wavelength of visible light is between 400 nm and 700 nm
The wavelength of ultraviolet ray on the range of 10 nm to 400 nm
The wavelength of photon is given by;
E = hf
f is the frequency of the wave = c / λ
Where;
c is the speed of light = 3 x 10⁸ m/s
h is Planck's constant = 6.626 x 10⁻³⁴ J/s
(a) 0.3 eV = 0.3 x 1.602 x 10⁻¹⁹ J
λ = 4136 x 10⁻⁹ m
λ = 4136 nm → infrared
(b) 3.0 eV
λ = 413.6 x 10⁻⁹ m
λ = 413.6 nm →visible light
(c) 30 eV
λ = 41.36 x 10⁻⁹ m
λ = 41.36 nm →ultraviolet