the answer is c I hope this helps
Answer:

Given:
Resistance (R) = 100 Ω
Current (I) = 5 A
Time (t) = 2 hours
To Find:
Heat developed (H) in the electric iron
Explanation:
Formula:

Substituting values of I, R & t in the equation:


Heat developed (H) in the electric iron = 15 kWh
Answer:
e) True Yes both are constant
Explanation:
Let us propose the solution of the problem before reviewing the statements, we use Newton's second law
F - fr = m a
N- W = 0
N = mg
The equation for the force of friction is
fr = μ N
F - μ mg = m a
F = m (a- μ g)
Now let's review the claims
.a) False. Normal force and friction are constants.
.b) False. Both are constant.
.c) False. Both are constant.
d.) False
e) True Yes both are constant
Planck's equation states that
E = hf
where
E = the energy,
h = Planck's constant
f = the frequency
Because
c = fλ
where
c = velocity of light,
λ = wavelength
therefore
E = h(c/λ)
Photon #1:
The wavelength is λ₁ = 60 nm.
The energy is
E₁ = (hc)/λ₁
Photon #2:
The energy is twice that of photon #1, therefore its energy is
E₂ = 2E₁ = (hc)/λ₂.
Therefore

Answer: 30 nm