Презентация к уроку "Резисторы" для 3 курсов СПО специальности МНЭО

Слайд #1

Resistors

Слайд #2

Aim:
Learn about resistors
Tasks:
1. learn new words
2. read the text about the resistors

Слайд #3

Read and put down the word:
capacity [kəˈpæsɪtɪ]- емкость
power [ˈpauə] - мощность
heat - теплота, нагрев
rate - скорость, степень
to produce [prəˈdjuːs] - производить
to change [tʃeɪndʒ] - менять(ся)
to vary [ˈvɛərɪ] - варьировать(ся)
low [lou] - низкий
high [haɪ]- высокий
fixed [fɪkst]- постоянный
any (зд.) - любой
variable [ˈvɛərɪəbl] - переменный
the (more) … the (more) - чем (больше) ... тем (больше)

Слайд #4

Слайд #5

Resistor
A resistor is one of the most common elements of any circuit. Resistors are used:
to reduce the value of current in the circuit;
2. to produce IR voltage drop and in this way to change the value of the voltage.
When current is passing through a resistor its temperature rises high. The higher the value of current the higher is the temperature of a resistor. Each resistor has a maximum temperature to which it may be heated without a trouble. If the temperature rises higher the resistor gets open and opens the circuit.

Read and translate the text.

Слайд #6

Resistors are rated in watts. The watt is the rate at which electric energy is supplied when a current of one ampere is passing at a potential difference of one volt. A resistor is rated as a 1-W resistor if its resistance equals 1,000,000 ohms and its current-carrying capacity equals 1/1,000,000 amp, since P = E × I = IR × I = I2R where P − power is given in watts, R − resistance is given in ohms and I − current is given in amperes.
If a resistor has a resistance of only 2 ohms but its current-carrying capacity equals 2,000 amp, it is rated as a 8,000,000-W resistor. Some resistors have a constant value − these are fixed resistors, the value of other resistors may be varied − these are variable resistors.
Read and translate the text.

Слайд #7

Run the test
1. A resistor is used a) to measure the resistance.
b) to reduce the current.
c) to change the resistance.
d) to produce IR voltage drop.
2. When current passes through a resistor a) its temperature drops.
b) its temperature rises.
3. Resistors are rated a) in ohms.
b) in volts.
c) in watts.

Слайд #8

Homework: run the test
4. Power is given a) in amperes.
b) in watts.
5. Fixed resistors have a) a constant value.
b) a variable value.
6. The value of a variable resistor a) is fixed.
b) is varied.
7. A two-ohm resistor rated as a 8,000,000-W resistor
a) has a current-carrying capacity equal to 2,000 amp.
b) has a current-carrying capacity equal to 200 amp.
8. The higher the value of current,
a) the lower is the temperature of a resistor.
b) the higher is the temperature of a resistor.