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Generating Electricity - Statistics
General Stats
- This quiz has been taken 9 times
- The average score is 6 of 32
Answer Stats
| Question | Answer | % Correct |
|---|---|---|
| What device is used to detect small electrical currents? | Galvanometer | 75%
|
| Magnetic field lines move away from which pole | The North Pole | 63%
|
| Who discovered the motor effect? | Michael Faraday | 50%
|
| What does emf stand for? | Electromotive force | 38%
|
| What is the name given to the amount of magnetic flux through a given area? | Magnetic flux | 38%
|
| In Faraday's initial experiment with two separate coils, there was a current induced into the coil with no battery. However this current was only _________. | Temporary | 38%
|
| What is magnetic field strength, B, measured in? | Tesla (T) | 38%
|
| Eddy currents also cause an increase in ____ which can be helpful in the kitchen. | Heat | 25%
|
| A faster moving magnet near a coil induces a ______ current. | Larger | 25%
|
| Opposes | 25%
| |
| In electric motors, an induced emf is created in the current-carrying coil because it is moving in a magnetic field. What direction compared to the current is the emf travelling? | The opposite direction | 25%
|
| When a load is added the coil rotates slower so back emf is reduced. This results in a higher current which could burn out the motor. What device is used to protect motors from an initially high current when they are switched on? | A series resistor | 13%
|
| What is this emf also known as? | Back emf | 13%
|
| When this happens no voltage and therefore no current passes through the coil. There is also now no net force on the coil so it rotates at a ________ ____. | Constant rate | 13%
|
| What is created every time a conductor moves through an external magnetic field or vice versa? They are an application of Lenz's Law. | Eddy currents | 13%
|
| What is the name for the generation of an emf through the use of a magnetic field? | Electromagnetic Induction | 13%
|
| Flux | 13%
| |
| Lenz's Law: An induced current always _____ ___ to a current that creates a magnetic field that _______ the original change in ____ through the circuit. | Gives rise | 13%
|
| What direction do these produced magnetic fields travel compared to the external magenetic field direction. (They travel in circles/whirls) | Perpendicular | 13%
|
| What is emf is inversely proportional to? | The change in time | 13%
|
| What law is Lenz's Law a consequence of? | The law of conservation of energy? | 13%
|
| Compared to moving a magnet into a coil, what direction does the deflection in the galvanometer read when the magnet is brought away from the coil. | The opposite direction | 13%
|
| It's symbol is the greek character phi, but what is it's SI unit? | Weber (Wb) | 13%
|
| By switching on an electromagnet close to a wheel, what can we use eddy currents for in cars and trains? | Electromagnetic breaking | 0%
|
| These devices create electromagnetic fields to induce eddy currents into detectable metals. These eddy currents place a load on the coil, changing the _________ of the oscillator. | Frequency | 0%
|
| The process of using this property in induction cookers and furnaces is called what? | Induction heating | 0%
|
| Faraday's second notable experiment on induced currents featured an ____ ____. This had a greater induced current but it was also ^. | Iron ring | 0%
|
| What is magnetic field strength is also known as when it passes through a given area? | Magnetic Flux Density | 0%
|
| What is the most common example of an induction switching device? | Metal detector | 0%
|
| In other words an "induced" magnetic field ______ what causes the change in flux through a circuit. | Repels | 0%
|
| If there is nothing to slow it down, the speed of the armature coil in a motor increases until the back emf is equal to what? | The external emf | 0%
|
| What is the magnitude of generated emf is determined by? | The rate at which the magnetic flux changes | 0%
|
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