What is the ammeter reading?

Given that $R_1=10 \mathrm{\Omega }, R_2=40 \mathrm{\Omega }, R_3=30 \mathrm{\Omega }, R_4=20 \mathrm{\Omega }$ and $R_A$ is the parallel combination of $R_1$ and $R_2$ whereas $R_B$ is the parallel combination of $R_3$ and $R_4$. Combination $R_A$ is connected to the positive terminal  of $12 \mathrm{V}$ battery while combination $R_B$ is connected to the negative terminal. Ammeter $A$ is connected between the resistors $R_A$ and $R_B$.

Find $R_A$ and $R_B$. Also, calculate total resistance in the circuit.

Given that $R_1=10 \mathrm{\Omega }, R_2=40 \mathrm{\Omega }, R_3=30 \mathrm{\Omega }, R_4=20 \mathrm{\Omega }$ and $R_A$ is the parallel combination of $R_1$ and $R_2$ whereas $R_B$ is the parallel combination of $R_3$ and $R_4$. Combination $R_A$ is connected to the positive terminal  of $12 \mathrm{V}$ battery while combination $R_B$ is connected to the negative terminal. Ammeter A is connected between the resistors $R_A$ and $R_B$.

Draw the circuit diagram showing above combinations connected to battery and ammeter.

An electric heater connected to a $220 \mathrm{V}$ line has two resistance coil of $22 \mathrm{\Omega }$ each. Calculate the current if these coils are used separately.

An electric heater connected to a $220 \mathrm{V}$ line has two resistance coil of $22 \mathrm{\Omega }$ each. Calculate the current if these coils are used in series.

An electric heater connected to a $220 \mathrm{V}$ line has two resistance coil of $22 \mathrm{\Omega }$ each. Calculate the current if these coils are used in parallel.

Two resistors of resistances $3 \mathrm{\Omega }$and $6 \mathrm{\Omega }$ respectively are connected to a battery of $6 \mathrm{V}$ so as to have maximum resistance. How will you connect the resistances in this case?