**Solutions: C**

Alternatively, you may put values to work out using the 2 basic formulae of P = IV and V = IR. Refer the video below.

**Solutions: C**

Alternatively, you may put values to work out using the 2 basic formulae of P = IV and V = IR. Refer the video below.

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Solutions: Option B

As **lamp X is thicker and shorter**, these 2 factors make the **resistance of X lower than Y**.

*Recall: Length increases, R increases & cross-sectional area increases, R decreases. *

*[R = pL/A]*

As both bulbs are connected to the same mains, (assume 240V), the potential difference across the bulbs are 240 V.

**Brightness of the bulb depends on power**, P = IV or V2/R, since V is constant, I across X is higher due to lower R,

hence **power of X is greater than power of Y, hence X is brighter**.

The diagram shows four lamps in front of a plane mirror. The card prevents the observer at X from seeing the lamps directly, although the image of one lamp can be seen in the mirror.

Which lamp’s image can be seen?

**Solution: B
**

An apartment block receives water from a nearby reservoir. A pump is necessary to lift the water into a storage tank at the top of the building.

The gravitational field strength is 10 N / kg. How much energy does the pump supply to lift each kilogram of water into the tank?

**Solutions: 100J**

Water will always find its own level. Hence with or without the pump, the water level in the pipe in the building will be of the same level as the reservoir. Hence, the pump is only needed to pump water up a height of 10m only (instead of the 50m).

Energy, E = mgh = 1 kg x 10 N/kg x 10m =** 100 J**