Higher Engineering Science end of year

Calculate the minimum required gain of the transistor.

• 343

• 456

• 243

• 379

• 325

Answer explanation

First calculate Ic using the Power and Voltage of the motor.

Then calculate 85% of the supply to the mosfet. Vout - Vbe = Vb.

Use Vb and Rb to calculate Ib.

Hfe = Ic/Ib

What material is considered Brittle?

• A

• B

• C

• D

Answer explanation

If there is no plasticity region then the material is considered brittle.

Calculate the required value of resistor, R, so that Vout reaches its maximum value when Vin is 0·68 V.

• 45KΩ

• 45Ω

• 32Ω

• 32KΩ

• 198.9kN

• 249·7kN

• 342.6kN

• 202.4kN

Calculate Vout when pin 4 and pin 6 are high and pin 5 is low.

• -12.5v

• 12.5v

• -13.2v

• 13.2v

Answer explanation

Vout = -Rf(V1/R1 + V2/R2) × -Rf/Ri = -12 (5/6 + 5/24) × -1

= 12·5 V

Calculate the reaction force at C, using the Principle of Moments

• 2.08KN

• 1.2KN

• 2.25KN

• 1.08KN

Calculate the Force of F by taking moments around P.

• 26.9kN

• 9.12kN

• 22.5kN

• 14.8kN

What are the advantages of using a MOSFET ? (more than 1 answer)

• MOSFETs are physically smaller than BJT transistors

• MOSFETs are not damaged by heat

• MOSFETs are controlled by current at the gate

• MOSFETs handle large input currents

What way will the Motor turn?

• Anticlockwise (Inverting)

• Clockwise (Non - Inverting)