Which of the following statements is NOT true | vedclass

Name: Exam Paper Generator | JEE NEET Paper Generator | Vedclass
Brand: Vedclass
Rating: 5 (35 reviews)

Question

(B) The power $P$ radiated by a linear antenna is given by the relation $P \propto \frac{l^2}{\lambda^2}$,where $l$ is the length of the antenna and $

Vedclass · Accepted Answer

Power radiated decreases with increasing frequency.

Vedclass · Answer

(B) The power $P$ radiated by a linear antenna is given by the relation $P \propto \frac{l^2}{\lambda^2}$,where $l$ is the length of the antenna and $\lambda$ is the wavelength.Since $P \propto l^2$,statement $A$ is true.Since $\lambda = \frac{c}{f}$,we have $P \propto \frac{l^2}{(c/f)^2} \propto f^2$. This means power radiated increases with the square of the frequency.Therefore,statement $B$ is false because it claims power decreases with increasing frequency.For efficient radiation,the antenna size $l$ must be comparable to the wavelength $\lambda$ (typically $l \geq \frac{\lambda}{4}$),so statement $C$ is true.Since long wavelength signals correspond to low frequencies,the radiated power $P \propto f^2$ is very small,making statement $D$ true.

Which of the following statements is $NOT$ true?

Similar Questions

$A$ message signal of frequency $f_m$ is used to modulate a carrier of frequency $f_c$. If the sidebands are $f_1$ and $f_2$, then the ratio $\frac{f_c}{f_m}$ is:

The mathematical form of an $AM$ wave is given by $e = 50 (1 + 0.5 \sin(2\pi \times 5 \times 10^3 t)) \sin(31.4 \times 10^6 t) \text{ V}$. The frequencies of the $LSB$ and $USB$ in the given $AM$ wave are,respectively,....... and ....... .

$A$ carrier wave of peak voltage $15 \,V$ is used to transmit a message signal. If the modulation index is $60 \%$, then the peak voltage of the modulating signal is (in $\,V$)

$A$ message signal of frequency $10 kHz$ is used to modulate a carrier wave of frequency $6 MHz$. The sideband frequencies are:

What is the modulation index of an over-modulated wave?

Vedclass Test Series

Exam Paper Generator

Online Exam Module