Luminous Intensity SI Units Quiz and Flashcards

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Questions and Answers

What is the unit of luminous intensity in S.I?

coulomb
ampere
ampere-hour
candela (correct)

What is the unit of electric current in S.I?

ohm
volt
ampere (correct)
watt

What is the symbol for the unit of luminous intensity?

C
cd (correct)
A
I

What is the symbol for the unit of electric current?

A (A) Signup and view all the answers

What are the two physical quantities associated with the units mentioned?

Electric current and luminous intensity (D) Signup and view all the answers

What does accuracy represent in the context of shooting?

Hitting the bull's eye (D) Signup and view all the answers

What is precision represented by in the context of shooting?

A tight grouping of shots (C) Signup and view all the answers

What is the accepted value in the context of shooting?

The bull's eye (A) Signup and view all the answers

What does a tight grouping of shots indicate in the context of shooting?

High precision (A) Signup and view all the answers

What is the difference between accuracy and precision in the context of shooting?

Accuracy is hitting the bull's eye, precision is a tight grouping of shots (C) Signup and view all the answers

What is the formula to calculate percentage error?

% Error = (YV - AV) x 100 ÷ AV (A) Signup and view all the answers

What is accuracy determined by?

The number of significant digits (D) Signup and view all the answers

What do AV and YV stand for in the percentage error formula?

Your Value and Accepted Value (B) Signup and view all the answers

What is an analogy used to demonstrate accuracy and precision?

Shooting at a target (C) Signup and view all the answers

What is the purpose of calculating percentage error?

To compare the measured value to the accepted value (B) Signup and view all the answers

What is the formula to calculate the percentage error?

(YV - AV) x 100 ÷ AV (A) Signup and view all the answers

What is the unit of the percentage error?

% (D) Signup and view all the answers

What happens to the meter unit during the division in the percentage error formula?

It cancels out (C) Signup and view all the answers

What is the value of AV in the given problem?

9.45 m (C) Signup and view all the answers

What is the percentage error in the given problem?

10.5 % (B) Signup and view all the answers

What is the conversion factor from inches to centimeters?

1 in = 2.54 cm (D) Signup and view all the answers

When converting units, why can units be treated as algebraic quantities?

Because units can be cancelled (B) Signup and view all the answers

What is the result of converting 15.0 in to centimeters?

38.1 cm (A) Signup and view all the answers

What is the advantage of treating units as algebraic quantities?

It allows for unit cancellation (B) Signup and view all the answers

Why is it important to know the correct conversion factor between units?

So that accurate results can be obtained (A) Signup and view all the answers

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Study Notes

Units and Measurements

The unit of luminous intensity is the candela (cd).
The unit of electric current is the ampere (A).

S.I. Accuracy

Determined by the number of significant digits.
Calculated by the formula: % Error = (YV – AV) x 100 ÷ AV

Accuracy and Precision

Demonstrated by shooting at a target:
- Accuracy: hitting the bull's eye (the accepted value)
- Precision: a tight grouping of shots (they are finely tuned)

Calculating Percentage Error

Formula: % Error = (YV – AV) x 100 ÷ AV
Where: YV is the student's measured value, AV is the accepted value
Example:
- YV = 8.46 m, AV = 9.45 m
- % Error = (8.46 m – 9.45 m) x 100 ÷ 9.45 m = -10.5%