Answer:
At the focus
Explanation:
In car head lights concave mirrors are used. The light bulbs in these headlights are place along the principal axis as shown in the figure. On this Principal axis light bulbs are place at the Focus to get maximum brightness. As from the figure we can conclude that light rays coming from infinity converse at focus thus, giving maximum brightness.
Answer:
Thumb
Explanation:
The direction of the magnetic field can be determined by using the right-hand rule. According to this rule, hold a current carrying wire in your right hand such that the thumb of the right-hand point in the direction of electric current. The curled finger gives the direction of the magnetic field.
Hence, the thumb shows the electric current.
Answer:

Explanation:
When two cars collide then the momentum of two cars will remains conserved
- Mass of two cars = 100 kg
-
Speed of car B = - 10 m/s
-
After collision the speed of car B = +8 m/s
By momentum conservation equation


One
If you use the right hand rule for these problems, you usually make your fingers and thumb sit at right angles to each other. What each of the two fingers means and that related to the thumb is a different story. All you have to understand at this point is that all three are mutually perpendicular.
That makes C the answer.
All the other choices don't make that clear.
Two
This is a straight definition question. The definition says exactly what D says.