Past Paper Qs (AS, May 2018) Flashcards
Which of the following increases as the temperature of a metallic conductor increases? (1)
A- amplitude of the vibrations of the lattice ions
B- distance travelled by the charge carriers between collisions
C- drift velocity of the conduction electrons
D- number of conduction electrons per unit volume
A- amplitude of vibrations of lattice ions
The graph shows how the potential difference V varies with the current I for a circuit component.
Which of the following could be the circuit component? (1)
A- diode
B- filament bulb
C- ohmic resistor
D- thermistor
B- filament bulb
A student carried out an experiment to determine the e.m.f of a cell.
The current in a circuit was changed by adjusting a variable resistor. A graph was plotted of the voltmeter reading on the y-axis against the ammeter reading on the x-axis.
Using the data obtained, the value of the y intercept was the e.m.f of the cell.
Which of the following circuits should’ve been used? (1)
A
Three resistors, of resistance R1,R2 and R3, are connected in series across a cell. The cell has e.m.f E with negligible internal resistance. The current through the cell is I.
Derive the formula for the total resistance Rt of the circuit in terms of R1,R2 and R3. (3)
. A statement applying the conservation of energy to the circuit
-E= V1 + V2 +V3
. Use of ohms law for each term, leading to the cancelling of currents in the equation.
-E= IRt= IR1 + IR2 + IR3
. Rt = R1 + R2 + R3
A thin wire of negligible mass is used to hang a picture on a wall. The wire is hung over a nail and can be attached to the picture using arrangement 1 or arrangement 2
(a) Deduce which wire arrangement should be used to keep tension in the wire as small as possible. (4)
. Weight of picture= vertical component of tension
.W = mg
Mg
—— = Tcos(angle between wire and vertical)
2
. As the angle (to the vertical) is smaller in arrangement 1, cosine of the angle will be larger.
. Arrangement 1, as tension in wire is lower than is arrangement 2
T= Mg
——
2 cos(angle between wire and vertical)
A thin wire of negligible mass is used to hang a picture on a wall.
(b) It was observed that if the wire was not hung with its midpoint over the nail, as in diagram 1, the picture moved and then remained in the position shown in diagram 2. (3)
. The weight doesn’t act through the nail (pivot)
- centre of gravity is not in line (below) pivot
- there’s a perpendicular distance between weight + nail
. There is now a moment of the weight
- anticlockwise moment is greater than clockwise moment
. Picture stops moving when the centre of gravity is below the nail
- anticlockwise moment= clockwise moment and picture is in equilibrium
Question 11 (a)
21 degrees
A teacher uses a linear air track to provide a frictionless surface for two gliders, each of mass m. She uses this, with a pair of light gates connected to a computer, to investigate the collision between the gliders.
The gliders are each given a small push and travel towards the centre of the track.
The gliders move off together.
(a) calculate the velocity of the gliders after the collision, using the principle of the conservation of linear momentum. (3)
Initial velocity of glider1= 0.3ms^-1 to the right
Initial velocity of glider2= 0.7ms^-1 to the left
. Use p=mv
.use principle of conservation of momentum (2mv because before collisions there were two momentum’s so after there must be as well)
- initial direction of glider 1 is positive)
- mx0.3 - mx0.7= 2mv
-0.3 - 0.7= v
————
2
. 0.2 ms^-1
To the left
A teacher uses a linear air track to provide a frictionless surface for two gliders, each of mass m. She uses this, with a pair of light gates connected to a computer, to investigate the collision between the gliders.
The gliders are each given a small push and travel towards the centre of the track.
The gliders move off together.
