Science- Batteries and Circuits

Why are resistors added to circuits? How do they work?

Devices called resistors let us introduce precisely controlled amounts of resistance into electrical circuits. ... A resistor works by converting electrical energy into heat, which is dissipated into the air. Resistors are added to circuits to limit current, and separate voltages. They are used to slow the power, like in a car volume system.

How do electromagnetic motors work? Describe the different parts and what purpose they serve.

Electromagnetic motors work by using electric and magnetic forces and wind wires to make force. They use torque on the motors shaft, and this generates the force, which powers the motor. Electromagnetic motors have 3 main parts: rotor, strator, and commutator. The stator is the stationary part of the AC motor. The rotor is the rotating electrical component. The commutator is a rotary electrical switch that periodically reverses the current direction between the rotor and the external circuit. They utilize the forces of electromagnetism (attraction and repulsion) making the motor spin as long as there is an electric current.

How do fiber optic cables transfer information? Why are they considered one of the best tools to use?

Fiber optic cables transfer information. They are made of thin, sensitive glass that is hair size. These strands are arranged to form called optical cables. The optical fiber transmits information through light, where the light signal is decoded and received as data. Fiber optic Internet sends data faster compared to cable. It's delivered on a specific line, which has more consistent speed than cable. Fiber optic Internet is less likely to stop in case of a blackout. Also it doesn't require electricity because fiber optic Internet is made of glass.

Electric motors utilize electric and magnetic forces to operate. Which of the following are expected to increase electric or magnetic forces and make the motor rotate faster? Explain.

Increasing the number of turns of wire in the motor's electromagnets - This is because the motor generates power through winding the wires, which means more of the winding would increase the power and make it rotate faster.

Compare voltmeter and anmeter (not from your school study guide)

Key Points A voltmeter is an instrument used for measuring electrical potential difference between two points in an electric circuit (voltage) An ammeter is a measuring device used to measure the electric current in a circuit. (current) A voltmeter is connected in parallel with a device to measure its voltage(because objects in parallel experience the same potential difference) while an ammeter is connected in series with a device to measure its current (This is necessary because objects in series experience the same current). At the heart of most analog meters is a galvanometer, an instrument that measures current flow using the movement, or deflection, of a needle. The needle deflection is produced by a magnetic force acting on a current-carrying wire. Voltmeters and ammeters measure the voltage and current, respectively, of a circuit.

How do batteries provide electricity? Do they provide voltage or current?

A battery is a device that stores chemical energy and converts it to electrical energy. The chemical reactions in a battery involve the flow of electrons from one material (electrode) to another, through an external circuit. The flow of electrons provides an electric current that can be used to do work.

Would you connect an ammeter in series or parallel? Would you connect a voltmeter in series or parallel? Explain.

An ammeter is always connected in series to the device. In order for an ammeter to measure a device's current, it must be connected in series to that device. This is necessary because objects in series experience the same current. A voltmeter is always placed in parallel to the circuit. The voltmeter is placed in parallel with the component of interest because components in parallel experience the same potential difference.

What is current? When does current flow?

An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. Current is flow of electrons, but current and electron flow in the opposite direction. Current flows from positive to negative and electron flows from negative to positive. Current is determined by the number of electrons passing through a cross-section of a conductor in one second.

When a flashlight is turned on, light waves propagate through the air. Which statements about light are correct? Explain.

Light is bent at the interface between materials. Light can bounce and turn like inside the glass tube, it can bend between materials. Light does not require matter to propagate either, so C and B are correct.

Describe the difference between connecting batteries in parallel versus in series.

The difference between connecting batteries in parallel versus series is that, when in series, 2 batteries are connected - - like that, while in parallel they are connected like // that. In a series connection, batteries are connected to increase the voltage but capacity remains the same. In a parallel connection, batteries are connected to increase the capacity but voltage remains the same. Voltage is how much energy the electron has as it MOVES. Capacity is how much energy is stored in each battery.

Explain the transformation of energy in a circuit that contains a battery and a lightbulb.

The energy is transformed from chemical energy to electrical energy. The bulb converts this electrical energy into light and heat energy.

How do wires provide resistance? Explain.

The relationship between resistance and wire length is proportional . The resistance of a thin wire is greater than the resistance of a thick wire because a thin wire has fewer electrons to carry the current. The relationship between resistance and the area of the cross section of a wire is inversely proportional . Wires provide more resistance when they're longer and thinner.

When we built a wet-cell battery, why did we separate the metal plates with blotter paper? Why did it continue working even when it was out of solution?

The wet cell battery absorbed the solution, and it continued working because it was still there, a bit of the solution. It was still damp, which meant not all of the zinc oxide was absorbed.

What is Ohm's Law? What is important about it?

V= I R OR Voltage = current X resistance Ohm's law is vitally important to describing electric circuits because it relates the voltage to the current, with the resistance value moderating the relationship between the two.

What is voltage? How can you measure voltage? Does it matter where you measure voltage?

Voltage is the electrical potential difference between two points in an electrical circuit. It is measured with a voltmeter. A voltmeter must be connected in parallel with a device to measure its voltage. This is necessary because objects in parallel experience the same potential difference.

If we were to use a voltmeter across batteries, what would we be measuring? If we were to measure voltage across a device, what would we be measuring?

When using a voltmeter across batteries, we'd be measuring voltage, or difference in potential energy. When using a voltmeter across a device, we'd be measuring IS IT ALSO VOLTAGE? Voltmeters always measure voltage so...

How do you measure current? Where would you find an ammeter in a circuit? Does it matter where you place a meter in a circuit?

You can measure current using an ammeter. It's measured in the unit of the ampere. It is placed in series in a circuit. The current is the same everywhere in a series circuit. It does not matter where you put the ammeter, it will give you the same reading.