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A lens produces a virtual image that is smaller than the object. Which one of the following is correct?      

A concave mirror produces an inverted image 3 times taller than the object. If the object is placed at 15 cm from the mirror, what is the focal length of the mirror?

A rectangular coil of 50 turns and the dimensions 20 cm by 30 cm is placed in a uniform magnetic field of 1.2 T. The coil rotates such that its orientation with the field changes from 30 degrees to 60 degrees in 0.1 second. What is the magnitude of induced emf in the coil?

A 250-turn solenoid carries a current of 5.0 A. The length of the solenoid is 14 cm. What is the magnetic field inside the solenoid?

A small bird of mass m is sitting on a perch of mass 7 g, which is supported by a magnetic force. The perch is 10 cm long and contains a wire carrying a current of 2.0 A. The perch is oriented at right angles to a uniform magnetic field of 0.9 T that is strong enough to support the perch and the bird. What is the mass of the bird?

The electric field at a point 2.0 cm from a small charged object has a strength of E=160,000 N/C and is directed towards the charge. What is the object’s charge?

A charge +5 

A plastic ball of mass 2.1 g has been charged to 3 nC.  What strength of the electric field will produce an acceleration of 0.5 m/s2 on the ball, if electrostatic force is the only force acting on the ball?

What is the equivalent resistance of the combination of resistors shown in the figure, if each resistor has 10 Ω (ohm) resistance?

A 16-year-old states: “I don’t know who I am anymore. I feel different around every group of friends.” According to Erikson, this adolescent is struggling with: