This physics problem tests your understanding of fundamental physical laws and their applications. The step-by-step solution below breaks down the problem using relevant equations and physical reasoning.
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Here are the solutions to your questions: 8. a. Figure 10 shows a photovoltaic plate with a power output of 30 mW cm^-2 and an efficiency of 40%. i) Determine the amount of solar energy falling on it per unit time. Step 1: Convert the given power output per unit area to standard units (Wm⁻²). I_out = 30 mW cm^-2 = 30 × 10^-3 W × (1 m100 cm)^2 I_out = 30 × 10^-3 W × (10^4)/( m)^2 = 300 Wm^-2 Step 2: Use the efficiency formula to find the power input per unit area (I_in). The efficiency () is given by: = Power output per unit area (I_out)Power input per unit area (I_in) Rearranging for I_in: I_in = I_out Step 3: Substitute the values and calculate. Given = 40\% = 0.40. I_in = 300 Wm^-20.40 I_in = 750 Wm^-2 The amount of solar energy falling on it per unit time (per unit area) is 750 Wm^-2. ii) How many such plates can supply energy directly to a 3 horse power electric pump switched on for 20 minutes if the intensity of solar radiation is assumed constant within this time and 1 hp = 800 W? Step 1: Calculate the total power required by the electric pump. Given pump power = 3 hp. P_pump = 3 hp × 800 W/hp P_pump = 2400 W Step 2: Calculate the surface area of one photovoltaic plate from the figure. A_plate = 1.5 m × 1.0 m A_plate = 1.5 m^2 Step 3: Calculate the total power output of one photovoltaic plate. Using the power output per unit area I_out = 300 Wm^-2 from part (i). P_out,plate = I_out × A_plate P_out,plate = 300 Wm^-2 × 1.5 m^2 P_out,plate = 450 W Step 4: Determine the number of plates required. N = Total power required by pumpPower output of one plate N = 2400 W450 W N = 5.333... Since you cannot use a fraction of a plate, you must round up to ensure the pump receives sufficient power. The number of plates required is 6 plates. 8. b. Explain why solar energy is referred to as being: i) Environmentally friendly: Solar energy is environmentally friendly because its generation process does not produce greenhouse gas emissions or other pollutants that contribute to air pollution, acid rain, or climate change. It utilizes a clean, natural resource. ii) Functional: Solar energy is functional because it can be directly converted into usable forms of energy, primarily electricity (via