Question

3. The focal power of a lens has the dimensions
(1) [L]
(2) [ML^2T^-3
(3) [L^-1]
(4) [MLT^-3]​

with solution

Answer 1

Quéstion :

• Calculate the dimensions of power of focal length.

Options :

• (1) [L]
• (2) [ML²T-³]
• (3) [L-¹]
• (4) [MLT-³]

Answer :

p = 1/f

where,

• p = power of focal length
• f = Focal length

Dimension of power of focal length :

p = 1/f

F is distance so dimension of Focal length is [L]

p = 1/[L]

p = [M⁰L-¹T⁰]

Hence

• Dimension of power of focal length is [M⁰L-¹T⁰] or [L-¹]
• Option (3) is correct

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