ELE 100
What are the effects of moving a closed wire loop through a magnetic field?
A voltage is induced in the wire, A current is induced in the wire, The polarity of the voltage across the wire depends on the direction of motion—All of the above
A transformer which has 1380 turns in its primary coil is to be used to convert the mains voltage of 230 V to operate a 6 V bulb. How many turns should the secondary coil of this transformer have?
ANS: 36 turns
AC frequency in US(United States)
ANS: 60 HZ
Will a transformer work with direct current (d.c.) or alternating current (a.c.)?
ANS: AC
Which one is NOT an essential part of a battery?
ANS: Acid
What would induce a greater electric current in a wire?
ANS: Adding more loops of wire
Which of the following is a primary cell?
ANS: Carbon-Zinc cell
The device that produces electricity from chemical reaction is called
ANS: Cell
Liquid in the cell is called
ANS: Electrolyte
________________ is the generation of current due to relative motion between a wire and a magnetic field
ANS: Electromagnetic Induction
At its most basic level, a battery is a can full of chemicals that produces ____.
ANS: Electrons
A group of batteries make up a cell.
ANS: False
Dry cells are normally used in cars and trucks
ANS: False
Step-up transformers are located near to end user
ANS: False
What is the most accurate statement on how warm temperature affects batteries?
ANS: Loss of battery life
Electrical Generator performs which kind of energy conversion?
ANS: Mechanical Energy to Electrical Energy
A disadvantage of mercury cells and batteries is the fact that_______________.
ANS: Mercury is destructive to the environment.
Who discovered the operating principle of electromagnetic generators?
ANS: Michael Faraday
The machine that converts electrical energy to mechanical energy is called
ANS: Motor
What is meant by a step down transformer?
ANS: One where the output voltage is smaller than the input voltage
In a transformer, the primary coil has twice as many loops as the secondary coil. This is a __________ transformer.
ANS: Step-up
The faster the coil of a generator rotates through the magnetic field the______________
ANS: The higher the output voltage.
What happens when you turn off the current in an electromagnet?
ANS: The magnetism is turned off
According to principle of electro-magnetic induction, generator produces voltage when there is a changing magnetic field.
ANS: True
The operation of an electrical generator relies on electromagnetic induction
ANS: True
Which of the following best describes the difference between wet cells and dry cells?
ANS: Wet cells have a liquid electrolyte, while in dry cells the electrolyte is a moist paste
AC generators are also called _______________, since they produce an alternating current.
ANS: alternators
Increasing the number of turns of wire on the secondary of a transformer will___________.
ANS: decrease the secondary current
The areas of a battery that are marked positive (+) and negative (-) are called:
ANS: electrodes
Electromagnetic induction is a term used to describe___________
ANS: production of electric potential due to change in magnetic flux
When the current through a coil reverses direction, the magnetic field around the coil _____.
ANS: reverses its direction
In 1800, Alessandro Volta made the first battery by layering plates of silver and zinc with blotting paper that had been soaked in salt water. What was this primitive battery called?
ANS: voltaic pile
What is 1 pF?
Ans: 10-12 F
A 10 µF, 20 µF, 22 µF, and 100 µF capacitor are in parallel. The total capacitance is
Ans: 152 µF
A 10 µF capacitor has a dc voltage of 200 V across its plates. What is the charge on the plates?
Ans: 2 mC
What is the charge on a 200 µF capacitor with 100 Volts across its terminals?
Ans: 20 mF
If a 0.001 μF capacitor is connected in series with an 800 pF capacitor, the total capacitance is___________
Ans: 444.444 pF
Find the capacitance of a parallel-plate capacitor if a 35 V potential difference exists with 2,000 µC of charge.
Ans: 57.14 µF
A charged capacitor acts like a _____________.
Ans: Battery
A capacitor has a capacitance of 1 farad if 1 ___________ of charge is deposited on the plates by a potential difference of 1 volt across the plates.
Ans: Coloumb
Removing magnetism from an object is sometimes called _____________
Ans: Degaussing
Which of the following capacitors is polarized?
Ans: Electrolytic
Unit for capacitance is_________
Ans: Farads
Naturally occurring magnets in nature are called:
Ans: Lodestones
This is a force where objects are attracted or repelled to one another
Ans: Magnetism
Capacitors in series combined like resistors in ________________.
Ans: Parallel
Electromagnetic induction is a term used to describe___________.
Ans: Production of electric potential due to change in magnetic flux.
How do you make an electromagnet?
Ans: Run current through a wire wrapped around an iron rod
Dielectric material determines the type of capacitor.
Ans: True
Electrolytic capacitors are used in rectifier circuits.
Ans: True
Magnetic flux flows from the North Pole to the South Pole.
Ans: True
The operation of an electrical generator relies on electromagnetic induction.
Ans: True
The voltage across a capacitor cannot change instantaneously
Ans: True
How can you show that electricity creates a magnetic field?
Ans: Use a compass near a wire with current flowing through it
A ferromagnetic material is _______________________.
Ans: a material that shows strong magnetic effects
You can tell if an object is magnetic if the groupings of atoms_____________ .
Ans: are lined up in the same direction
For an electromagnet, an increase in current through the coil
Ans: increases the magnetic lines of force
A magnet made of a material that keeps its magnetism is known as_______________.
Ans: permanent magnet
When the current through a coil reverses direction, the magnetic field around the coil _____.
Ans: reverses its direction
A Capacitor ____________
Ans: stores energy
When the plate area of a capacitor increases,
Ans: the capacitance increases
