From each diagram, find focal length for each please
From each diagram, find focal length for each please
For a concave mirror, the point at which the reflected rays meet on the principal axis, when the incident rays are parallel to the mirror’s principal axis is its focus.
The intersection point of the mirror with its principal axis is the mirror’s pole.
The separation of the pole from the focus is nothing but the mirror’s focal length.
For a concave lens, the point where the extrapolated refracted rays meet on the principal axis, when the incident rays are parallel to the lens’s principal axis is its focus.
The intersection point of the lens’s optical axis with its principal axis is the lens’s optical center.
The separation of the optical center from the focus is nothing but the lens’s focal length.
In the given figure of the concave mirror, the focus (F) and the pole (P) can be identified by using their definitions.
Then, their separation may be determined by using the given scale as follows:
On the ruler, the pole (P) and the focus (F) can be seen to have a separation of 9.4 ruler-units and the 10 cm-scale can be seen to have the separation of 6.3 ruler-units.
This means that 6.3 units of distance on the ruler is equivalent to 10 cm of actual distance.
Let f1 denote the focal distance in this case.
Evaluate the mirror’s focal length in cm by using the conversion factor obtained as follows:
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