3º EM - 1st Physics Activity - Sector A

 1-) An electric current of magnitude 3.0 A flows through a resistor of electrical resistance 20 ohms. Determine:

a-) the electrical power consumed by the resistor;

b-) the electrical energy consumed in the interval of 20 s.

2-) An electric shower reads the inscription 2200W – 220V.

a-) What is the electrical resistance of the shower when in operation?

b-) When correctly connected, what is the current intensity that crosses it?

c-) With the shower turned on correctly, what should be done in its electrical resistance to increase the electrical power dissipated?

3-) Double the voltage applied to a resistor. What happens to the power it dissipates?

4-) A resistor dissipates 60 W of power when connected at voltage of 220 V. Assuming invariable the electrical resistance of the resistor, determine the electrical power dissipated in it when connected at voltage of 110 V.

5-) An electric faucet supplies 2 liters.min-1 of water at a temperature of 40°C, and the temperature of the water at the inlet is 20°C. The electrical resistance of the faucet is 28 ohms. Calculate the amount of electric current flowing through the faucet resistor.

Data: density of water 1 kg.liter-1, specific heat of water 1,0 cal.g-1.°C-1 and 1 cal = 4.2J

6-) In 0.5 kg of water contained in a container, initially at 25 °C, a resistor of electrical resistance 2.0 ohms is immersed for 7 min. If an electric current of 5.0 A flows through the resistor, calculate the temperature of the water after this time interval. Data: specific heat of water 1,0 cal.g-1.°C-1 and 1 cal = 4.2J