Answer:
For a concave mirror, the magnification (m) is negative. The magnification formula is given by:
\[ m = -\frac{f}{u} \]
where:
- \( m \) is the magnification,
- \( f \) is the focal length,
- \( u \) is the object distance.
Given \( f = -30 \) cm (negative because it's a concave mirror) and \( m = -\frac{1}{3} \), you can solve for \( u \) using the formula. Substituting the values:
\[ -\frac{1}{3} = -\frac{30}{u} \]
Now, solve for \( u \):
\[ u = 90 \, \text{cm} \]
So, the object should be placed 90 cm in front of the concave mirror to achieve a magnification of \( \frac{1}{3} \).
