Question

Відстань між стіною і свічкою 4 м. Між ними розмістили збиральну лінзу на відстані 3 м від стіни. Визначити фокусну відстань лінзи, якщо на стіні утворюється чітке зображення свічки.​

Answer 1

Calculation of the focal length of the lens

To determine the focal length of the lens, we can use the lens formula:

1/f = 1/v - 1/u

Where: - f is the focal length of the lens - v is the image distance (distance between the lens and the image) - u is the object distance (distance between the lens and the object)

In this case, the object is the candle and the image is formed on the wall.

Given: - Distance between the wall and the candle (object distance, u) = 4 m - Distance between the lens and the wall (image distance, v) = 3 m

Let's substitute these values into the lens formula to find the focal length (f):

1/f = 1/3 - 1/4

To simplify the calculation, we can find the common denominator:

1/f = (4 - 3) / (3 * 4)

1/f = 1/12

Now, we can find the reciprocal of both sides to get the value of f:

f = 12

Therefore, the focal length of the lens is 12 meters.

Please note that the focal length is positive, indicating that the lens is a converging lens (convex lens).