If the power of a lens is +4 D. The lens has a focal length of: An object is pla

Question

If the power of a lens is +4 D. The lens has a focal length of: An object is placed 50cm in front of a concave mirror with focal length of 25 cm. What is (in absolute value) the magnification produced by the mirror? The unit of electric energy is: An ideal transformer has 75 turns on its primary coil and 850 turns on its secondary coil. If 150 V is applied to the primary, what voltage is present in the secondary? Which of the following is a vector A parallel plate capacitor with a capacitance of 0.2 mu F is to be operated at 6500 v. The charge on the plates is: R_1 = 20 ohm and R_2 = 10 ohm are connected in series to a 30V battery. The heat dissipated for 1h in R1 is: The magnetic field at 2 cm distance from a long straight wire, carrying a 2A electric current is: An electric motor: The voltage through a circuit is v = 0.8 sin 314t What is the amplitude of the voltage ?

Explanation / Answer

According to the given problem,

24.) Given P = +4D , we know that f = 1/P

f = 1/4 = 0.25m = 25 cm

25.) Using the lens equation,

1/u + 1/v = 1/f

1/50 + 1/v = 1/25

1/v = 1/25

v = 25

And M = -v/u = -25/50 = -1/2 units

26.) The unit for electrical energy is,

Every day useage is kWh or 3.6*106J

27.) For a Ideal transformer,

Np/Ns = Vp/Vs

75/180 = 150/Vs

Vs = 360 V

Only 4 sub-parts in a single question, please repost the remining questions separatly.

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