SATHEE: Electric Charges and Fields

Electric Charges and Fields - Result Question 2

2. Two metal spheres, one of radius $R$ and the other of radius $2 R$ respectively have the same surface charge density $σ$ . They are brought in contact and separated. What will be the new surface charge densities on them? [NEET Odisha 2019]

(a) $σ_{1} = \frac{5}{3} σ, σ_{2} = \frac{5}{6} σ$

(b) $σ_{1} = \frac{5}{6} σ, σ_{2} = \frac{5}{2} σ$

(d) $σ_{1} = \frac{5}{2} σ, σ_{2} = \frac{5}{3} σ$

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Answer:

Correct Answer: 2. (a)

Solution:

(a) $Q_{1} = σ 4 π R_{1}^{2} = σ 4 π R^{2}$ $Q_{2} = σ 4 π (2 R)^{2} = σ 16 π R^{2}$

After redistribution

$\begin{aligned} (i) & \frac{Q_{1}^{'}}{Q_{2}^{'}} = \frac{R}{2 R} \Rightarrow Q_{2}^{'} = 2 Q_{1}^{'} \\ (ii) & Q_{1}^{'} + Q_{2}^{'} = 20 σ π R^{2} \end{aligned}$

From eq. (i) and (ii)

$\begin{aligned} Q_{1}^{'} = \frac{20}{3} σ π R^{2} \Rightarrow σ_{1}^{'} = \frac{5}{3} σ \\ Q_{2}^{'} = \frac{40}{3} σ π R^{2} \Rightarrow σ_{2}^{'} = \frac{5}{6} σ \end{aligned}$

Electric Charges and Fields - Result Question 2

2. Two metal spheres, one of radius $R$ and the other of radius $2 R$ respectively have the same surface charge density $σ$ . They are brought in contact and separated. What will be the new surface charge densities on them? [NEET Odisha 2019]

Answer:

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Electric Charges and Fields - Result Question 2

2. Two metal spheres, one of radius R and the other of radius 2R respectively have the same surface charge density σ. They are brought in contact and separated. What will be the new surface charge densities on them? [NEET Odisha 2019]

Answer:

Engineering Preparation

Medical Preparation

NCERT Books & Solutions

Important Resources

Other Resources

Syllabus

Test Platform

Sample Mock Test

Mentorship

NCERT Exercise Video Solution

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2. Two metal spheres, one of radius $R$ and the other of radius $2 R$ respectively have the same surface charge density $σ$ . They are brought in contact and separated. What will be the new surface charge densities on them? [NEET Odisha 2019]