Science Unit 5
What is the difference between an electromagnet and a permanent magnet?
A permanent magnet cannot be turned off, and it has set north and south poles, its domains point one direction. An electromagnet also has a north and south pole, but you can turn it off. When the current changes direction, so does the polarity of the magnet and the direction of the domains
What is one difference between a galvanometer and an electric motor?
An electric motor uses electrical energy, while a galvanometer measures electrical current
You should use a potholder when getting a cookie sheet out of the oven because of what type of heat transfer?
Conduction
What are the 3 main methods of heat transfer?
Conduction, convection, radiation
Temperature
Degree of hotness, measure of the average kinetic energy (speed) of molecules in a sample, dependent on movement of molecules
When a wire with a current is placed in a magnetic field...
Electrical energy is transformed into mechanical energy
Radiation
Energy that is radiated or transmitted in the form of rays or waves or particles.
A hot object is placed next to a cold object so that they are touching. What will happen?
Heat will transfer from the hot object to the cold object because the hot object has a higher temperature
When you touch an ice cube, it feels cold because
It steals heat from your hard
An electric current produces a
Magnetic field
Explain why it is relatively easy to remove baked potatoes from a hot barbecue without a hot pad if they are wrapped in aluminum foil
Metal absorbs heat really well but also loses heat easily
On a cold day, you grab a shiny, metal fence gate with your bare hand. The post feels very cold. The next gate is made of wood and does not feel cold. Both gates are at the same temperature because they are close together outside. Explain why one gate feels colder than the other
Metal has higher conductivity-will lose heat much easier than wood
An aluminum can and a paper bowl have been sitting out in the sun for 2 hours. They started at room temperature. After 2 hours, the aluminum can's temperature had raised 25 degrees, while the paper bowl had only raised its temperature by 5 degrees. Which likely has the higher specific heat?
Paper bwol
Convection
Process by which, in a fluid being heated, the warmer part of the mass will rise and the cooler portions will sink.
Heat
Quantity of hotness; energy that is transferred between objects of different temperature, dependent on mass, specific heat, and change in temperature.
Thermal conductivity
The ability of an object to transfer heat
Ice cream left out on the counter melts because_______
The air gave its heat to the ice cream
Specific Heat capacity
The amount of heat required to raise the temperature of 1 gram of a substance by 1 degree Celsius. How well an object stores heat
Conduction
The direct transfer of heat from one substance to another substance that it is touching.
Specific Heat
The energy required to raise 1g of substance 1 degree Celsius; how well an object can store or retain heat; a higher specific heat will take more energy to raise its temperature
Temperature
The measure of the average kinetic energy of all the particles in the object. The atoms mass and speed determine the temperature of the object
Equal amounts of heat are absorbed by 100g samples of various solid metals with differing specific heat values. Which of the following statements is true regarding metals and their specific heat values?
The metal with the greatest specific heat will undergo the smallest change in temperature
Faraday's Law
The more coils on an electromagnet, the stronger the magnetic field is. When you move magnets in and out of coils, it produces an electric current
Heat
The quantity of thermal energy an object has. It only transfers when objects have different temperatures
A glass of cold water is placed in a sealed room. After an infinite amount of time, what will happen?
The water will warm and the air will cool until they are the same temperature
To reverse the direction of current in a motor, current is conducted
Through the brushes to the commutator
According to the law of conservation, energy can be ____________, but not created or destroyed
Transferred
You can increase the strength of an electro magnets field by
Using a stronger ferromagnetic material for the core
Electromagnet
a coil that has a soft iron core and that acts as a magnet when an electric current is in the coil
Kinetic Energy
energy of motion
Formula for Calculating heat
q = mcΔT
Potential Energy
stored energy
Energy
the ability to do work
Thermodynamics
the study of energy transformations
