A convex lens of focal length 15 cm produces a magnification of +4. The
1 answer:
Focal length = 15cm
Magnification = +4
Type of lens : <u>convex</u>
We have to find distance of object..
★ <u>Lateral Magnification :</u>
m = v/u
- v denotes distance of image
- u denotes distance of object
4 = v/u
v = 4u
★ Lens Formula :-
→ 1/v - 1/u = 1/f
Focal length of convex lens is taken +ve and that for concave lens is taken -ve.
→ 1/4u - 1/u = 1/15
→ -3/4u = 1/15
→ u = -45/4
→ u = -11.25 cm
∴ (D) is the correct answer
You might be interested in
Answer:
a) Fg = -27.4 N
b) Fnet = 5.2 N
c) a = 1.9 m/s2
Explanation:
a)
- There are two forces acting on the ball, one directed upward (assuming this direction as positive, along the y-axis) which is the tension on the string (lifting force), and another aimed downward, which is the attractive force due to gravity.
- Applying the Newton's Universal Law of Gravitation to a mass close to the surface of the Earth (in this case the ball), we can take the acceleration due to gravity like a constant, that we call by convention g, equal to -9.8 m/s2.
- So, we can write the following expression for Fg:
b)
- The net force on the ball, will be just the difference between the lifting force (32.6 N) and the force due to gravity, Fg:
c)
- According Newton's 2nd Law, the acceleration caused by a net force on a point mass (we can take the ball as one) is given by the following expression: