Answer:
25 cm
Explanation:
Since, in the question it is given that the final image after reflection through the convex lens and then the reflection by the plane mirror is formed at the pinhole itself.
This means that the pinhole must be at the focus of the convex lens, such that the lens makes the ray perpendicular to the mirror and hence focal length of the lens = 25 cm.
Answer:
1. False
2. True
3. True
Explanation:
1- False —> The relation between electric potential and electric field is given such that

Therefore, for a uniform E field, electric potential is linearly proportional to the distance.
2- True —> The electric field lines always cross the equipotential lines perpendicularly.
3- True —> In order to be a potential difference, one source of electric field is enough. The electric potential will decrease radially according to the following formula:

There is no test charge in the formula, only the source charge. Even when there is no test charge, the potential difference between points in space can exist.
Copper is a reddish orange, soft metal with a bright metallic luster. It is an excellent conductor of heat and electricity. Copper surfaces when exposed to air gradually turns to a dull, brownish color.
<span>The strength of the gravitational force between two objects depends on two factors,mass and distance. the force of gravity the masses exert on each other. If one of the masses is doubled, the force of gravity between the objects is doubled. increases, the force of gravity decreases.</span>
Answer:
The arrow was moving at 16.2 m/s
Explanation:
The law of conservation of energy says that the kinetic energy of the arrow must be converted into the potential energy of the block and arrow after it they join:

where is the mass of the arrow, is the mass of the block, of the change in height of the block after the collision, and is the velocity of the arrow before it hit the block.
Solving for the velocity v, we get:



The arrow was moving at 16.2 m/s