ENNYSTON SCIENCE COMPETITION: 3RD ROUND - SENIOR 3

1.   A conductor of length 2m carries a current of 0.8A while kept in a magnetic field of magnetic flux density 0.5 T. The maximum force acting on it is

                               

• A.  0.2 N

•   B. 0.8 N

• C. 3.2 N

• D. 8.0 N

  If two parallel conductors carry currents flowing in the same direction, the conductors will

                                       

• A.  Attracts each other  

• B. repel each other 

• C. both move in the same direction

• D. have no effect on each other

  A transformer has primary coil with 500 turns and a secondary coil with 2500 turns. When the voltage input to the primary coil is 120 V, the output is

                                 

• A.  6000 V

• B. 600 V

•   C. 240 V

•    D. 60 V

  In a radio circuit, the a.c voltage across a resistor is given by V = 4sin60. Calculate the frequency of the a.c.

                   

• A.  30 Hz

•    B. 60 Hz

•     C. 30 s

• D. 60 s

1.   X       +       ⁴₂He          ------à        ¹³₇N   +       ¹₀n   

The atomic number and mass number of X in the equation above are respectively

                                                  

• A.  5 and 9

• B. 5 and 10

•    C. 9 and 13 

• D. 9 and 14

Evaluate 625^3/4

• (a) 125

• (b)-25

• (c) ¹/₂₅

• (d) 5^-2

Differentiate 4x(3x + 5) with respect to x

• 12x2 + 20x

• 24x + 20x

• 24x + 20

• 24 + 20x

Integrate 1/x with respect to x

• 0

• In2x

• x2/2

• Inx

• 10

• 25

• 55

• 5

Simplify (¹/_√3) - (²/_√2).

• (a)¹/₆(5√3 - 3√2)

• (b) ¹/₆(15√3 - 6√2)

• (c)¹/₆(3√2 - √3)

• (d) ¹/₆(2√3 - 6√2)