Measurement of the focal length of a concave mirror

Label this diagram

a - light box

b - slit

c - card

d - concave mirror

e - meter stick

f - image distance

g - object distance

Demonstrate the method of this experiment • 1

• Move card back and forth until a sharp image of the slit is formed

Demonstrate the method of this experiment • 2

• Measure and record u and v using the metre stick

• Repeat previous steps by changing the distance

Demonstrate the method of this experiment • 3

• Calculate the focal length using the distance formula

• Calculate the average of f for each set of values

Define 3 precautions that are associated with this experiment • 1

Keep card close to ruler to measure v accurately

Define 3 precautions that are associated with this experiment • 2

Measure u and v from the back of the mirror

Define 3 precautions that are associated with this experiment • 3

Keep card vertical

Label This Formula

The Distance Formula

v - image distance

u - object distance

f - focal length

When is u positive and negative?

U is always positive

Never negative

When is v positive and negative?

Positive - Real Images

Negative - Virtual Images

When is f positive and negative?

Positive - Concave Mirrors

Negative - Convex Mirrors

What page of the log tables can you find the Distance formula?

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