SECTION - B [PHYSICS - NUMERIC] - JEE STD 11 Science Questions

Question 14 Marks

Two particles are located at equal distance from origin. The position vectors of those are represented by $\overrightarrow{ A }=2 \hat{ i }+3 n \hat{ j }+2 \hat{ k }$ and $\vec{B}=2 \hat{i}-2 \hat{j}+4 p \hat{k}$, respectively. If both the vectors are at right angle to each other, the value of $n ^{-1}$ is__________.

Answer

$\overrightarrow{ A } \cdot \overrightarrow{ B }=0$
$
\begin{array}{l}
4-6 n+8 p=0 \\
|\overrightarrow{A}|=|\overrightarrow{B}| \\
4+9 n^2+4=4+4+16 p^2 \\
9 n^2=16 p^2 \\
P=+\frac{3}{4} n \\
4-6 n \pm 6 n=0 \\
12 n=4 \\
n=\frac{1}{3}
\end{array}
$

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Question 24 Marks

A positive ion A and a negative ion B has charges $6.67 \times 10^{-19} C$ and $9.6 \times 10^{-10} C$, and masses $19.2 \times 10^{-27} kg$ and $9 \times 10^{-27} kg$ respectively. At an instant, the ions are separated by a certain distance r. At that instant the ratio of the magnitudes of electrostatic force to gravitational force is $P \times 10^{-13}$, where the value of $P$ is __________ .
(Take $\frac{1}{4 \pi \varepsilon_0}=9 \times 10^9 Nm ^2 C ^{-1}$ and universal gravitational constant as $6.67 \times 10^{-11} Nm ^2 kg^{-2}$ )

Answer

(BONUS)
$\frac{9 \times 10^9 \times 6.67 \times 10^{-19} \times 9.6 \times 10^{-10}}{6.67 \times 10^{-11} \times 19.2 \times 10^{-27} \times 9 \times 10^{-27}}$ $\frac{1}{2} \times 10^{45}$Charge is not integral multiple of electron.

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JEE SECTION - B [PHYSICS - NUMERIC]

SECTION - B [PHYSICS - NUMERIC]

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