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Answer

Power = 1/Focal length

Focal length = 1/Power = 1/0.2 = 5m

Hence, none of the options are correct.

Answer

A lock-out relay is heavy duty relay used in critical applications where the safety of equipment is of top priority.

Normal relays are used only for tripping the system whereas a lock-out relay locks out the system and needs to be reset manually thereby preventing the damages caused by remote reset of the system.

Lock-out relays are generally used in transformers, generators etc.

e.g. If a transformer trips due to action of Bucholz relay, a lock-out relay (if present) will prevent further damage by not allowing remote reset. Manual recognition of the fault intensity and manual reset is required

Answer

Let the number be x

Calculated value = 2x/3 = 0.67x

Correct value = 3x/2 = 1.5x

%error = (Calculated value - True value)/True value = (0.67 - 1.5)/1.5 = -55.5%

Answer

Since the month starts on a saturday.

We will have 5 Sundays and 5 Mondays and all the other days will be four.

Total no. of visitors = 5 x 250 + (30 - 5) x 100 = 3750

Average no. of visitors per day = 3750/30 = 125

 

Answer

Work = Force x Displacement

Part (i)

Force on the barbell = m x g = 275 x 9.8 = 2695 N

Displacement = 2.4 m

Work = 2695 x 2.4 = 6468 N

Part (ii)

Displacement = 0

Work = 0

 

Answer

Focal length = 10 mm = 0.01 m Power = 1/Focal length = 1/0.01 = 100 D

Answer

No. of ways of picking up three balls = 15C3 = 455

No. of ways of picking up two green balls = 6C2 = 15

No. of ways of picking up a blue ball = 5C1 = 5

Required probability = (15 x 5) ÷ 455 = 15 / 91