Q160 / 160 · TS EAMCET 2022 (19 Jul Shift 2) · Physics
Which of the following statements is NOT true?
- APower radiated from a linear antenna is directly proportional to square of antenna length
- Correct answerBPower radiated decreases with increasing frequency.
- CAntenna should have size comparable to the wavelength of the signal
- DEffective power radiated by a long wavelength baseband signal is small
Solution
We have
$\mathrm{P} \propto \frac{\mathrm{l}^2}{\lambda^2}$
So (a) is true
$\text {as, } \mathrm{P} \propto-\Rightarrow \mathrm{P} \propto \mathrm{f}$
So, (b) is false and (d) is true as, length of antenna $\geq \frac{\lambda_{\mathrm{C}}}{4}$ So, (c) is true
$\mathrm{P} \propto \frac{\mathrm{l}^2}{\lambda^2}$
So (a) is true
$\text {as, } \mathrm{P} \propto-\Rightarrow \mathrm{P} \propto \mathrm{f}$
So, (b) is false and (d) is true as, length of antenna $\geq \frac{\lambda_{\mathrm{C}}}{4}$ So, (c) is true
Hence, the correct answer is option: 'B'.