Two narrow parallel slits illuminated by a coherent monochromatic light produces an interference pattern on a screen placed at a distance $$\mathrm{D}$$ from the slits. The separation between the dark lines of the interference pattern can be increased by
Three point charges are located on a circular arc at $$\mathrm{A}, \mathrm{B}$$ and $$\mathrm{C}$$ as shown in the figure below. The total electric field at the centre of the $$\operatorname{arc}(\mathrm{C})$$ is
A voltmeter of resistance $$1000 \Omega .0 .5 \mathrm{~V} /$$ div is to be converted into a voltmeter to make it to read $$=1 \mathrm{~V} / \mathrm{div}$$. The value of high resistance to be connected in series with it is
Column - I lists the waves of the electromagnetic spectrum. Column - II gives approximate frequency range of these waves. Match Column - I and Column - II and choose the correct match from the given choices.
Column I | Column II | ||
---|---|---|---|
(A) | Radiowaves | (P) | $$ 10^{18} \text { to } 10^{20} \mathrm{~Hz} $$ |
(B) | Microwaves | (P) | $$ 10^{11} \text { to } 5 \times 10^{14} \mathrm{~Hz} $$ |
(C) | Infrared | (R) | $$ 10^4 \text { to } 10^8 \mathrm{~Hz} $$ |
(D) | X-rays | (S) | $$ 10^9 \text { to } 10^{12} \mathrm{~Hz} $$ |