Year 6 Science Cells, brightness and volume: check-up and practice test questions

Method. Recall the fact.

1. Recall. A standard cell gives 1.5 volts.
   1.5
2. Write the answer.
   1.5 volts

Check. Each cell adds 1.5 volts. ✓

Method. Multiply by 1.5 volts.

1. Multiply. Three cells give 3 x 1.5 volts.
   3 x 1.5 = 4.5
2. Write the answer.
   4.5 volts

Check. 1.5 + 1.5 + 1.5 = 4.5. ✓

Method. Read the mean column.

1. Read the row. The mean brightness for three cells is 5 out of 5.
   5
2. Write the answer.
   5

Check. Three trials of 5 give a mean of 5. ✓

Method. Read the table.

1. Read the table. The buzzer with one cell is rated 2 out of 5.
   2
2. Write the answer.
   2

Check. One cell is the quietest in the table. ✓

Method. Subtract the two totals.

1. Read the totals. Three cells give 4.5 volts, and two cells give 3.0 volts.
   4.5 and 3.0
2. Subtract. The difference is 4.5 minus 3.0.
   4.5 - 3.0 = 1.5
3. Write the answer.
   1.5 volts

Check. One extra cell adds 1.5 volts. ✓

Method. Recall the part.

1. Recall. A bulb lights up when current flows through it.
   bulb
2. Write the answer.
   bulb

Check. A buzzer makes a sound instead. ✓

Method. Recall the part.

1. Recall. The wire carries the current round the loop.
   wire
2. Write the answer.
   wire

Check. A gap in a wire stops the current. ✓

Method. Recall the idea.

1. Recall. A gap stops the current, so the bulb does not light.
   stops
2. Write the answer.
   no

Check. The loop must be complete. ✓

Method. Recall the name.

1. Recall. A complete circuit is joined all the way round.
   complete circuit
2. Write the answer.
   complete circuit

Check. A complete circuit lets current flow. ✓

Method. Think about the voltage.

1. Think about the voltage. Three cells give a higher total voltage than one cell.
   higher voltage
2. Think about the current. So more current flows through the bulb.
   more current
3. Write the answer.
   Accept any sentence that says three cells give a higher total voltage, so more current flows and the bulb is brighter.

Check. The voltage is the cause of the change. ✓

Method. Multiply by 1.5 volts.

1. Multiply. Four cells give 4 x 1.5 volts.
   4 x 1.5 = 6.0
2. Write the total. So the total is 6.0 volts.
   6.0 volts
3. Write the answer.
   6.0 volts

Check. Four times 1.5 is 6.0. ✓

Method. Read the ratings.

1. Read the ratings. The rating for two cells is 4 out of 5.
   4
2. Write the answer.
   4

Check. The ratings rise as the cells increase. ✓

Method. Subtract the one-cell rating from the three-cell rating.

1. Read the ratings. The ratings are 5 for three cells and 2 for one cell.
   5 and 2
2. Subtract. The difference is 5 minus 2.
   5 - 2 = 3
3. Write the answer.
   3

Check. 2 + 3 = 5. ✓

Method. Think about the voltage.

1. Think about the voltage. Two cells give a higher total voltage, 3.0 volts, than one cell, 1.5 volts.
   higher
2. Think about the current. So more current flows and the bulb is brighter.
   more current
3. Write the answer.
   Accept any sentence that says two cells give a higher total voltage, so more current flows and the bulb is brighter.

Check. Higher voltage gives more current. ✓

Method. Multiply by 1.5 volts.

1. Multiply. Three cells give 3 x 1.5 volts.
   3 x 1.5 = 4.5
2. Write the answer.
   4.5 volts

Check. Each cell adds 1.5 volts. ✓

Method. Think about the current.

1. Think about the current. With a gap in the loop, the current cannot flow round the circuit.
   cannot flow
2. Decide. So the bulb is off, and the reason is the gap.
   gap
3. Write the answer.
   no; gap

Check. A complete loop is needed. ✓

Method. Find the thing that changes on purpose.

1. Read the test. The number of cells is the one thing changed on purpose.
   number of cells
2. Write the answer.
   number of cells

Check. The others are fixed. ✓

Method. Think about safety.

1. Think about the risk. A wire joined across a cell is a short circuit, which makes it hot.
   short circuit
2. Think about the check. A teacher can check the connections to prevent this.
   prevent
3. Write the answer.
   Accept any sentence that says the teacher can check that no wire is joined across a cell, which prevents a short circuit.

Check. Safety comes first. ✓

Method. Check the voltage and the rating.

1. Check the cells. Two cells give 2 x 1.5 volts, which is 3.0 volts.
   2 x 1.5 = 3.0
2. Decide. The rating of 3 is out of 5 and is a class rating, not a voltage, so Ruby is not right.
   no
3. Write the answer.
   no

Check. The rating is not the same as the voltage. ✓

Method. Think about a fair test.

1. Think about the bulb. A different bulb may be brighter for its own reasons.
   own reasons
2. Think about fairness. So the test would not be fair if the bulb changed.
   not fair
3. Write the answer.
   Accept any sentence that says a different bulb could be brighter for another reason, so the test would not be fair.

Check. Keep the fixed variables the same. ✓