The correct answer is: (A) are in A.P.
The given expressions are:
\( p\left(\frac{1}{q} + \frac{1}{r}\right), q\left(\frac{1}{r} + \frac{1}{p}\right), r\left(\frac{1}{p} + \frac{1}{q}\right) \)
These expressions are stated to be in Arithmetic Progression (A.P.). In an A.P., the difference between consecutive terms is constant. Therefore, the second term minus the first term should equal the third term minus the second term:
Let’s calculate the differences:
After simplifying these expressions, we find that the condition for the terms to be in A.P. holds true when p, q, and r are in arithmetic progression (A.P.).
Thus, the correct answer is (A) are in A.P..
In an experiment to determine the figure of merit of a galvanometer by half deflection method, a student constructed the following circuit. He applied a resistance of \( 520 \, \Omega \) in \( R \). When \( K_1 \) is closed and \( K_2 \) is open, the deflection observed in the galvanometer is 20 div. When \( K_1 \) is also closed and a resistance of \( 90 \, \Omega \) is removed in \( S \), the deflection becomes 13 div. The resistance of galvanometer is nearly:
A wooden block of mass M lies on a rough floor. Another wooden block of the same mass is hanging from the point O through strings as shown in the figure. To achieve equilibrium, the coefficient of static friction between the block on the floor and the floor itself is