Physics

Which of the following describes a changing magnetic field for a generator to produce electric current?

• Both the magnet and the electric conductor should be steady.

• Either the magnet or the electric conductor should be moving.

• A.   Both the magnet and the electric conductor should be moving.

• A.   Current is induced whether the magnet and the electric conductor are      steady or moving.

You made an electric motor in school. When you tested it by using 4 dry cells, the armature turned very fast. What should you do to make it turn slower?

• Use a bigger magnet.

• Remove one of the dry cells.

• Increase the number of turns in the coil of wire.

• Decrease the distance between the magnetic poles. 

If a 100 W light bulb is lit for 8 hours each day for 20 days in a month, how many kilowatt-hours will the bulb consume? 

• 16

• 160

• 1600

• 16000

Mr. Simbajon’s electric meter reads 8765 kWh last month. How much will he pay for the power generation if the charge of the electric company per kWh is P6.88 and his electric meter this month reads 9975? 

• P 1,210.00

• P 3,457.42

• P 8,324.80

• P 8,756.00

When power reaches the distribution lines, the step-down transformer reduced further the voltage to 220 to 230 volts for household consumption. What will happen to an appliance labeled with 110-volt if it is plugged directly into our sockets?

•   It will burn or explode due to excess voltage or emf

• It will function but will not last long because the voltage is not        compatible.

• Its voltage will automatically change according to the voltage in the        power supply

• It will work properly since the voltage indicated in an appliance is not         associated with the voltage in the power supply

How do you find the combined resistance in a series and parallel circuit?

• R_total = R₂ = R₁ - R₃

• Rtotal = R1 + R2 - R3 

• R_total = R₁ – R₂ + R₃

•      Rtotal = R1 + R2 + R3 

A 625kg vehicle has a velocity of 10m/s. what is the car’s kinetic energy?

•    31,250J

•   50,250J

•   139,450J

• 239,450J

A speed boat has an acceleration of 2/ms2. What would the final velocity of the speedboat be after 5 seconds?

• 14m/s

• 16m/s

• 10m/s

• 12m/s

A vehicle has an acceleration of 5m/s.What would the final velocity of the vehicle be after 10 seconds if the initial velocity of the vehicle is 20m/s?what is the displacement?

• 435 m

• 459m

• 450m

• 500m

A child on a top of the hill starts from rest and accelerates down the hill at 8m/s. How long does it take the child to reach the bottom of the hill if it is 25m away.

• 7.9 sec

• 7.8 sec

• 7.5sec

• 7.4 sec