For longer wavelength, size of antenna would increase.
Also, mixing of signals needs to be avoided.
Also, we can use modulation to send low frequency signal by superimposing them with high frequency signals.
The correct option is (C): (a), (c) and (d) are true only
A conducting bar moves on two conducting rails as shown in the figure. A constant magnetic field \( B \) exists into the page. The bar starts to move from the vertex at time \( t = 0 \) with a constant velocity. If the induced EMF is \( E \propto t^n \), then the value of \( n \) is _____. 
The main properties of waves are as follows –