Given below are two statements: One is labelled as Assertion A and the other…
2023
Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R.
Assertion A: In concentrating type solar collector temperature can be raised up to 500°C.
Reason R: In concentrating type solar collector, the magnitudes of collector area and absorber area are numerically same.
In the light of the above statements, choose the most appropriate answer from the options given below
Answer: C. A is correct but R is not correct — CONCEPTA concentrating solar collector uses mirrors or lenses to intercept direct solar radiation over an aperture and focus it onto a smaller receiver or…
- A.
Both A and R are correct and R is the correct explanation of A
- B.
Both A and R are correct but R is NOT the correct explanation of A
- C.
A is correct but R is not correct
- D.
A is not correct but R is correct
Show answer & explanation
Correct answer: C
CONCEPT
A concentrating solar collector uses mirrors or lenses to intercept direct solar radiation over an aperture and focus it onto a smaller receiver or absorber. Its geometric concentration ratio is Cg = Aa/Ar, where Aa is aperture area and Ar is receiver area; for a concentrating geometry, Cg is greater than 1. The resulting higher flux density can support receiver temperatures of several hundred degrees Celsius, subject to optical and thermal losses.
APPLICATION
Evaluate Assertion A: concentrating collectors can operate at temperatures around 500°C, so the stated temperature capability is valid.
Evaluate Reason R: equality of aperture and receiver areas would give Cg = 1. A concentrating collector instead directs radiation from a larger aperture to a smaller receiver, so the stated area equality is not valid.
Combine the evaluations: A is correct, whereas R is not correct.
CONTRAST
“Both A and R are correct and R explains A” requires the equal-area statement to be valid and causal; Cg = 1 rules out concentration.
“Both A and R are correct but R does not explain A” still requires the equal-area statement to be valid; it is not a concentrating geometry.
“A is not correct but R is correct” reverses both evaluations: concentrating collectors can reach the stated temperature range, while their aperture and receiver areas are not equal.
CROSS-CHECK
If Aa were equal to Ar, Cg would be 1 and there would be no geometric concentration. With Aa greater than Ar, solar power collected over the aperture is focused onto the smaller receiver, which is consistent with high-temperature operation. Therefore, A is correct but R is not correct.