10_klass cost calculations of work and power

mechanical

light

thermal

electromagnetic

Work and power of electric current

10.3.2.4 – to make cost calculations of work and power of home appliances;

Work current - the work of the electric field to move the charge. Denoted by: А

Electric current power - work, which makes the current per unit of time. Р

Ammeter
Voltmeter
Clock

In practice, the work of electric current is measured by counters.

Counters - instruments for measuring the operation of electric current

Wattmeter - a device for measuring power

1 W•h = 3600J

1 kW•h=1000 W•h=3 600 000J

You need to know the power of all electrical appliances and the running time.To determine the consumption and cost of electricity (without meter)just use the formula:A = P · t, where P is the power of the electrical device (electrical appliances) in kWh;The power of the electrical device is recorded in the passport of the electrical device or on the bodyt is the operating time of the appliance in hours;A - the amount of electricity consumed, furtherC = A · tariff - the cost of electricityOrС = P · t · tariff (tenge / kW · h)

There is an electric lamp, designed for a current of 100 watts. The lamp is lit daily for 6 hours. Find the current work for one month (30 days) and the cost of energy consumed at a rate of 8.43 tenge / kWh.
Given:

Р = 100 W
t = 6h · 30 days= 180 h
Tariff = 8,43 tenge / kW·h


А - ?
С - ?

Decision
А = Р · t
А = 100 W·180h = 18 000 W·h = 18 kW·h.
С = А · Tariff
С = 8,43 tenge /(kW·h) ·18 kW·h = 151,74 tenge
answer: А = 18kW·h, С = 151,74 tenge

This method determines the consumption and cost of electrical energy (without a meter)

Denote the power consumption by R, [R] = [kW / h]

readings of the electric meter at the beginning of the period
(for example, at the beginning of the month)

- meter readings at the end of the period (for example, at the end of the month)

Energy consumption calculated by the formula

The cost of energy consumed will be found by multiplying the tariff for consumption:

C = Tariff · R

I1= 07787 kW/h at the beginning of the month  
I2 =07953 kW/h at the end of the month
I=07953-07787= 166 kW/h
energy consumption per month.
С = 13.64 tenge / kW / h · 166 kW/h .

Task 1. There is an electric lamp, designed for a current of 100 watts. The lamp is lit daily for 6 hours. In the office of 30 lamps. Find the current work for one month (30 days) and the cost of energy consumed at a tariff of 8.43 tenge per 1 kWh.
Task 2. There is an electric lamp, designed for a current of 100 watts. The lamp is lit daily for 6 hours. In the office of 30 lamps. The school has 50 classrooms. Find current work for one month (30 days) and the cost of energy consumed at a rate of 13.64 tenge per 1 kWh.
Task 3. There is an electric stove, designed for a current capacity of 10,000 watts. Daily working for 10 hours. In the dining room 4 plates. Find current work for one month (30 days) and the cost of energy consumed at a rate of 13.64 tenge per 1 kWh.
Task 4. In the office of computer science 15 computers with a capacity of 800 watts, which operate for 5.5 hours per day. What is the power consumption for 24 working days? The cost of electricity for the period at a cost of 13.64 tenge / kW · h.

Task 5. Iron power 1200 watts. Calculate the current work for 15 minutes of work. Translate the resulting value in kWh. Calculate how much you will pay for using this iron for 15 minutes of continuous operation at a rate of 11 tenge 53 tiyn.Task 6. In the household electric cooker, designed for a voltage of 220 V, there are two spirals, the resistance of each of which in the operating mode is 80.7 Ohms. With the help of a switch, one helix, two helixs in series or two helixes in parallel can be included in the network. Find power in each case.Task 7. Explain why, when two lamps of 40 and 100 W are switched on in series, the first one burns much brighter than the second.

1. What kind of light bulb do you buy for use in a nightlight - 40 W or 100 W? Why?

2. On the heating element of the kettle accumulated scale. How does this affect the boiling time of water? Why?

3. Why on irons, hair dryers, el. the plates set the temperature control?

1. Why do I need to save electricity?

4. What are some ways to save energy?

3. Do we need you to be rational and careful with electricity?

2. Does the power consumption depend on the season?

Turn on the light if you need it;

Wipe the bulbs and lamps frequently (if they are dirty, the illumination in the apartment may decrease by 10-15%).

Prefer buying energy-saving light bulbs;

When painting rooms, use light colors of paints (a light wall reflects almost 85% of the incident light);

Use light bulbs of varying power depending on need;