The power of a lens of focal length 0.5 m is :

Options

A. + 5 D
B. + 2D
C. - 5D
D. + 1D

Answer

To find the power of a lens given its focal length, we can follow these steps:

### Step 1: Understand the Formula for Power
The power (P) of a lens is given by the formula:
\[ P = \frac{1}{f} \]
where \( f \) is the focal length of the lens in meters.

### Step 2: Identify the Focal Length
In this problem, the focal length \( f \) is given as 0.5 meters.

### Step 3: Substitute the Focal Length into the Formula
Now, substitute the value of the focal length into the formula:
\[ P = \frac{1}{0.5} \]

### Step 4: Calculate the Power
Perform the calculation:
\[ P = \frac{1}{0.5} = 2 \, \text{diopters} \]

### Step 5: Determine the Type of Lens
Since the power is positive (2 diopters), we can conclude that the lens is a convex lens, which means it converges light.

### Final Answer
The power of the lens is \( 2 \, \text{diopters} \).

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