Magnetic Effects of Electric Current — Science STD 10 — Question

What is meant by “electric power”? Write the formula for electric power in terms of potential difference and current.

Identify the device used as a spherical mirror or lens in following cases, when the image formed is virtual and erect in each case.

Object is placed between infinity and device, image formed is diminished and between focus and optical centre on the same side as that of the object.

Why can you not use a concave mirror as a rear-view mirror in vehicles?

A current-carrying straight wire is held in exactly vertical position. If the current passes through this wire in the vertically upward direction, what is the direction of magnetic field produced by it? Name the rule used to find the direction of magnetic field.

What is the difference between a real image and a virtual image? Give one example of each type of image.

State the law of combination of resistances in parallel.

A vertical ray of light strikes the horizontal surface of some water:

1. What is the angle of incidence?
2. What is the angle of refraction?

Explain why, we cannot see our seats first when we enter a darkened cinema hall from bright light but gradually they become visible.

An object is placed at a distance of 30 cm from a concave lens of focal length 15 cm. List four characteristics (nature, position, etc.) of the image formed by the lens.

Four resistances of 16 ohms each are connected in parallel. Four such combinations are connected in series. What is the total resistance?