A concave lens has a focal length of 25 cm. What is the image distance when the object is placed at 50 cm?
Practice Questions
1 question
Q1
A concave lens has a focal length of 25 cm. What is the image distance when the object is placed at 50 cm?
-16.67 cm
-25 cm
-50 cm
-75 cm
Using the lens formula, the image distance is calculated to be -16.67 cm.
Questions & Step-by-step Solutions
1 item
Q
Q: A concave lens has a focal length of 25 cm. What is the image distance when the object is placed at 50 cm?
Solution: Using the lens formula, the image distance is calculated to be -16.67 cm.
Steps: 6
Step 1: Understand the lens formula, which is 1/f = 1/v + 1/u, where f is the focal length, v is the image distance, and u is the object distance.
Step 2: Identify the values given in the problem. The focal length (f) of the concave lens is -25 cm (negative because it's a concave lens) and the object distance (u) is -50 cm (negative because the object is on the same side as the incoming light).
Step 3: Substitute the values into the lens formula: 1/(-25) = 1/v + 1/(-50).
Step 4: Simplify the equation: 1/v = 1/(-25) + 1/50.
Step 5: Find a common denominator to combine the fractions: 1/v = -2/50 + 1/50 = -1/50.
Step 6: Invert the fraction to find v: v = -50 cm.
