Light with an average flux of \(20~\text{W/cm}^2\) falls on a non-reflecting surface at normal incidence having a surface area \(20~\text{cm}^2\). The energy received by the surface during time span of \(1\) minute is:
1. \(12\times 10^{3}~\text{J}\)
2. \(24\times 10^{3}~\text{J}\)
3. \(48\times 10^{3}~\text{J}\)
4. \(10\times 10^{3}~\text{J}\)
1. | \(1:1\) | 2. | \(1:c\) |
3. | \(1:c^2\) | 4. | \(c:1\) |
A capacitor is made of two circular plates each of radius \(12~\text{cm}\) and separated by \(5.0~\text{cm}.\) The capacitor being charged by an external source. The charging current is constant and equal to \(0.15~\text{A}.\) The displacement current across the plates is:
1. \(0\)
2. \(0.14~\text{A}\)
3. \(0.16~\text{A}\)
4. \(0.15~\text{A}\)
A parallel plate capacitor is made of circular plates each of radius \(R=6.0~\text{cm}\) has a capacitance \(C=100~\text{pF}.\) The capacitor is connected to a \(230~\text V\) AC supply with an (angular) frequency of \(300~\text{rad/s}.\) The amplitude of \(\vec{B}\) at the point \(3~\text{cm}\) from the axis between the plate is:
1. \(1.12\times 10^{-11}~\text T\)
2. \(2.01\times 10^{-12}~\text T\)
3. \(1.63\times 10^{-11}~\text T\)
4. \(1.01\times 10^{-12}~\text T\)
1. | in the \({x\text{-}y}\) plane and they are parallel to each other. |
2. | in the \({x\text{-}y}\) plane and they are mutually perpendicular to each other. |
3. | in the \({y\text{-}z}\) plane and they are mutually perpendicular to each other. |
4. | in the \({z\text{-}x}\) plane and they are parallel to each other. |
A radio can tune in to any station in the \(7.5\) MHz to \(12\) MHz bands. What is the corresponding wavelength band?
1. \(40\) to \(25\) m
2. \(10\) to \(100\) m
3. \(50\) to \(60\) m
4. \(20\) to \(10\) m
The amplitude of the magnetic field part of a harmonic electromagnetic wave in a vacuum is \(B_0=510~\text{nT}\). What is the amplitude of the electric field part of the wave?
1. \(200~\text{N/C}\)
2. \(153~\text{N/C}\)
3. \(150~\text{N/C}\)
4. \(510~\text{N/C}\)
Suppose that the electric field amplitude of an electromagnetic wave is \(E_0 = 120~\text{N/C}\) and that its frequency is \(\nu = 50.0~\text{MHz}.\) The value of propagation constant \(k\) is:
1. \(2.01~\text{rad/m}\)
2. \(1.72~\text{rad/m}\)
3. \(1.05~\text{rad/m}\)
4. \(2.41~\text{rad/m}\)