1. Take out 2.1A Data Sheet. We will have fifteen minutes to COMPLETE the data individually. We will work together as a class to get the data tables completed. As you answer questions, I will come by and stamp HW Bellringer: 2.1A Data Sheet

2. Data Table 1 DescriptionValue Circumference (cm) 14.4 Circumference (m) circumference (cm) / 100 Total mass (gm) 750 Total mass (kg) total mass (gm) / 1000 Force (hanging mass) total mass (kg) × 9.8 Torque (wheel and axle) force (hanging mass) × radius of the wheel (m)

3. Data Table 2 DescriptionValue Weight (spring scale) 0.4 N Reading (spring scale) 2.2 N Total force (N) weight (spring scale) + reading (spring scale) Length (lever arm) – (cm) 6.5 Length (lever arm) – (m) length (lever arm) – (cm) / 100 Torque total force (N) × length (lever arm) – (m)

4. Data Table 3 DescriptionValue Reading (spring scale) 2.2 N Total force 2.62 N Initial height (cm) 1.5 Final height (cm) 30.5 Distance (weight moved) (cm) final height (cm) – initial height (cm) Conversion formuladistance (weight moved) (cm) / 100 Distance (weight moved) (m) Angle (lever arm movement) Input torque Input work input torque × angle (lever arm movement) Output work total force × distance (weight moved) (m) Percent efficiency (output work / input work) × 100% 2.6 From Data Table 2

5. Let’s make a Foldable!!  Three half sheets of paper.  Fold as shown in the image.  Glue or staple the edges into the paper above it.  Ready to fill in!!

7. Question 1  Flap 1 What is an Electrical Field? Answer (under top flap so it doesn’t show)  A collection of charges creates an electrical field  A force does work on an object and in an electrical system, forces are applied to charged objects by an electrical field.  Potential difference in a field results in charge moving and doing work in an electrical system.

8. Question 2  Flap 2 What is the formula for electrical force? What is the formula for voltage difference? Answer (Under Flap 1) q = Charged = Distance E = Electrical field F E = Electrical force  V = Voltage difference F E = E x q  V = E x d Now that we know the formulas for electrical force and Voltage difference, we can use them to figure out WORK in an ELECTRICAL SYSTEM.

9. Question 3  Flap 3 What is work in an electrical system and how do you calculate for it? Answer (Under Flap 2, top half) Column 1: Electrical work is the product of potential difference and charge moved Work = Potential difference x Charge moved **Remember that Work = Force x Distance, but electrical work is a little different ** So let’s start with what we know W = F E x d W = ( E x q) x d W = (E x d) x q W =  V x q Units: Joules (J) =Volts (V) x Coulombs (C)

10. Question 3  Continued  Bottom Half  Sample problem  A car battery is being charged. For 15 minutes, 800 C of charge are deposited in the battery by an average potential difference of 8V. How much electrical work is done by the charger? G U E S

11. Question 4  Flap 4 What is electrical current and how do you calculate for it? Answer (Top Half) Column 1  Current is the rate at which charge flows.  Current is measured in Coulomb/sec and represented by I.  C/s = Ampere (A), which is the unit for current  I = q/  tor q = I x  t  To get electrical work, W = V x q, or W = V x I x  t Units  A = C/secorC = A x sec

12. Question 4 continued  Bottom Half  Sample problem  A 12-volt DC electric motor uses a current of 4 amperes (A). Find the electrical work done to operate this motor for 2 minutes.  G U E S

13. Question 5   What are the effects of electrical work and how to measure its efficiency?  Electrical work produces movement, thermal energy, light and sound in your everyday life.  But the device using the electrical work can’t use 100% of the electrical work. A motor for example gets warm; Heat is a By-product.  % Efficiency = Output work/Input work x 100% *** Hint: Output work is usually more than input work therefore never 100% efficient (meaning energy is lost)

14. Now remember to glue it into your notebook on Page 66

15. Exit Slip: Get it Stamped!!! Now I Know What did you learn today?? On Page 65 fill in the blanks using complete sentences/thoughts. Now I know That ________________ I still want to know ________________________. I am glad that I learned that__________________ because__________________________________.