Verified Solution • 2025–26 Session moderate

QJEEM19Phb533: JEE Main 2019 Physics - Class 12 JEEM19Phb533 Solution: The bob of a simple pendulum has mass 2g and a charge of 5.0…

The bob of a simple pendulum has mass 2g and a charge of 5.0 μC. It is at rest in a uniform horizontal electric field of intensity 2000 V/m. At equilibrium, the angle that the pendulum makes with the vertical is : (take g = 10 m/s2)

Multiple Choice Options

  • A tan–1(5.0)
  • B tan–1(2.0)
  • C tan–1(0.5)
  • D tan–1(0.2)

Step-by-Step Verified Solution

Tcos θ\theta = mg

Tsin θ\theta = qE

tan θ\theta = qEmg{{qE} \over {mg}}

tan θ\theta = 5×10−16×20002×10−3×10=12{{5 \times {{10}^{ - 16}} \times 2000} \over {2 \times {{10}^{ - 3}} \times 10}} = {1 \over 2}

⇒\Rightarrow tan⁡−1(12)=tan⁡−1(0.5){\tan ^{ - 1}}\left( {{1 \over 2}} \right) = {\tan ^{ - 1}}\left( {0.5} \right)

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