28.Capacitance. Consider a 10μF parallel plate capacitor initially connected to a 5-V DC power supply. The potential applied to the capacitor is then increased to 10V. What happens to the capacitanceof the capacitor? A.It will be doubled B.It will be quadrupled C.It will be halved D.It will be quartered E.It will remain the same 29.Energy. A parallel plate capacitoris connected to a battery. While connected to the battery, the area of each plate is increasedby a factor of 2. What happens to the energy storedin the capacitor? For the next two numbers, consider an isolated parallel plate capacitor with an initial charge100μC. A dielectric κis then inserted into the capacitor. The energyof the capacitor becomes 500μJ. The initial potential energy is 750μJ. 30.Charge. What happens to the chargeof the capacitor? 31.Dielectric. What is the value of κ?

National Institute of Physics 1stSem AY 2012-2013 Physics 7232.Capacitance.Two capacitors C1=C and C2=4C are connected in parallel to a 3-V battery. Which of the following statements is always TRUEabout the charge stored and voltage across each capacitor?A.VC1< VC2 ; QC1< QC2B.VC1< VC2 ; QC1= QC2C.VC1> VC2 ; QC1= QC2D.VC1= VC2 ; QC1< QC2E.VC1= VC2 ; QC1> QC233.Effective capacitance.Consider the following diagrams at the right. Assume that each of the capacitors has capacitance equal to C. Which has the highest effective capacitance?For the next two numbers, consider a parallel plate capacitor which consists of plates of area 1cm2, separated by 2mm. 34.Parallel plate capacitor.The capacitor is connected to a 10-V battery. What is the electric field between the plates? 35.Dielectric Slab.If a dielectric slab (κ=2) is then placed in between the plates, what will be the new electric field due to the plates of the capacitor?36.Dielectrics. Two dielectric slabs are placed inside a capacitor as shown in the figure. Which of the following circuit diagrams on its right corresponds to the capacitor combination?

National Institute of Physics 1stSem AY 2012-2013 Physics 7237.Current Density. The current density Jin a wire is given by 50.0 A/m2 i. If the drift velocity of the charge carriers (q = -0.1 C) is –2.0 x 10-4m/s i, what is the concentration of the carriers?38.Ohm’s Law. Three different materials A, Band Ceach have resistivities ρA> ρB>ρC. Assuming that the current densitiesin all materials are the same, rank the three in order of increasing electric field magnitude.