Period T = 1/f

T = 1/0.5 Hz

T = 2.0 seconds.

**Answer:**

The image behind the mirror is called a virtual image because it cannot be projected onto a screen—the rays only appear to originate from a common point behind the mirror. If you walk behind the mirror, you cannot see the image, because the rays do not go there

**Answer:**

(a) 441 W (b) 0.59 hP

**Explanation:**

Given that,

Mass of a woman, m = 60 kg

Height of a staircase, h = 15 m

Time, t = 20 s

(a) We need to find the power she expend. Work done per unit time is called power. It is given by :

( b) Since, 1 hP = 745.7 W

P = 0.59 hP

**Answer:**

The terminal voltage will be 5.99 volt.

**(d) is correct option.**

**Explanation:**

**Given that,**

Voltage = 6.00

Internal r= 0.8322 ohm

Total resistance R =7380 ohm

**We need to calculate the current**

**Using current formula**

Put the value into the formula

**We need to calculate the voltage drop due to internal resistance**

Now, The terminal voltage will be

**Hence, The terminal voltage will be 5.99 volt,**

<em>optical</em><em> </em><em>fibre</em>